Rupert  Beatty

Rupert Beatty

1667066940

Watchdog: Class for Logging Excessive Blocking on The Main Thread

Watchdog

Class for logging excessive blocking on the main thread. It watches the main thread and checks if it doesn’t get blocked for more than defined threshold.

👮 Main thread was blocked for 1.25s 👮

You can also inspect which part of your code is blocking the main thread.

Usage

Simply, just instantiate Watchdog with number of seconds that must pass to consider the main thread blocked. Additionally you can enable strictMode that stops the execution whenever the threshold is reached. This way, you can inspect which part of your code is blocking the main thread.

let watchdog = Watchdog(threshold: 0.4, strictMode: true)

Don't forget to retain Watchdog somewhere or it will get released when it goes out of scope.

Requirements

  • iOS 8.0+, tvOS 9.0+ or macOS 10.9+
  • Swift 5.0

Installation

Carthage

Add the following to your Cartfile:

github "wojteklu/Watchdog"

Then run carthage update.

Follow the current instructions in Carthage's README for up to date installation instructions.

CocoaPods

Add the following to your Podfile:

pod 'Watchdog'

You will also need to make sure you're opting into using frameworks:

use_frameworks!

Manually

Manually add the file into your Xcode project. Slightly simpler, but updates are also manual.

Download Details:

Author: Wojteklu
Source Code: https://github.com/wojteklu/Watchdog 
License: MIT license

#swift #macos #debugging 

What is GEEK

Buddha Community

Watchdog: Class for Logging Excessive Blocking on The Main Thread
Oral  Brekke

Oral Brekke

1675381680

Create Tic Tac toe with JavaScript (Free Code)

Do you want to make a Simple Tic-Tac-Toe game using JavaScript?

In this article you will learn how to create tic tac toe game using html css and javascript. If you are a beginner in JavaScript then Tic Tac Toe Game is perfect for you. This simple javascript game will help you improve your knowledge of javascript.

Create Tic Tac Toe with JavaScript

Earlier I shared another Simple Tic-Tac-Toe JavaScript game for beginners. So I made this design in a very advanced way. Here basically we will play with the computer that is we will play with the computer.

To create this tic-tac-toe javascript first I created the basic structure by html. Then I designed it with css and finally activated this project (tic tac toe javascript code against computer) with javascript.

Tic-tac-toe Game in JavaScript

JavaScript Tic Tac Toe is a simple game where two players take turns marking a grid of 3×3 squares, typically using X and O symbols. JavaScript is a programming language that can be used to create interactive websites and games, such as a Tic Tac Toe game.

A JavaScript implementation of Tic Tac Toe would involve creating a grid of squares using HTML and CSS, and then using JavaScript to handle the logic of the game, including determining the winner and allowing players to take turns.

As you can see above this is an advanced Tic Tac Toe game that I made with javascript. Like a normal JavaScript Tic Tac Toe game, there are 9 cells and two symbols.

Here I have defined symbol “0” for user and “X” for computer. But you can change it if you want. When you click in any one of those 9 cells, another cell will automatically be filled by the computer.

Besides, I have added different types of color FF in the project (tic tac toe javascript code against computer) to make this design more modern.

How to make tic tac toe in HTML CSS and JavaScript

Now if you want to build it then you can follow the tutorial below. I have explained the complete codes step by step keeping the beginners in mind.

Hope you know the rules of this game. It is a simple javascript game where two players take turns marking the spaces in a 3×3 grid with X’s and O’s, with the goal of getting three of their marks in a row, either horizontally, vertically, or diagonally. The player who succeeds in placing three of their marks in a row is the winner.

Step 1: Basic structure of Tic Tac Toe game

First I created a basic structure of this project using the following HTML and CSS codes. Besides, I have added a heading here mainly to enhance the beauty. This heading is created by H1 tag in HTML. 

<div class="container">
  <h1>Tic-Tac-Toe</h1>

</div>
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: Arial, Helvetica, sans-serif;
}

.container {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: #eee;
}

h1 {
  font-size: 4rem;
  margin-bottom: 0.5em;
}

Basic structure of Tic Tac Toe game

Step 2: Create a place to play Tic Tac Toe games

Now create a small area for this tic tac toe javascript. Within this box are nine smaller boxes into which players can input their symbols. Also we designed this area by some css.

<div class="play-area">

</div>
.play-area {
  display: grid;
  box-shadow: 0 0 20px rgba(0,139,253,0.25);
  grid-template-columns: auto auto auto;
  background-color: #fff;
  padding: 20px;
}

Create a place to play Tic Tac Toe games

Step 3: Results of the JavaScript Tic Tac Toe game

Now another heading we need to create is within this project(How to Build Tic Tac Toe with JavaScript, HTML and CSS). This heading is mainly for showing results. 

Although this heading is currently not visible to us because there is no information in the heading. We will add this information via javascript. Results will be available automatically after Tic Tac Toe game is over.

<h2 id="winner"></h2>
h2 {
  margin-top: 1em;
  font-size: 2rem;
  margin-bottom: 0.5em;
}

Step 4: Create the game's restart button

Now we have to create a button in this simple Tic-Tac-Toe game. This button will basically work as a reset button. When you click on this button, the game will restart from a new state.

<button onclick="reset_board()">RESET</button>
button {
  outline: none;
  background: rgb(8, 88, 208);
  padding: 12px 40px;
  font-size: 1rem;
  font-weight: bold;
  color: #fff;
  border: none;
  transition: all 0.2s ease-in-out;
}

button:hover {
  cursor: pointer;
  background: green;
  color: white;
}

Results of the JavaScript Tic Tac Toe game

Step 5: Activate Simple Tic-Tac-Toe with JavaScript

Above we have designed this project(How to create a tic tac toe grid in JavaScript?). Now it’s time to make it work using JavaScript. We have used quite a bit of JavaScript code to make this game work. But don’t worry I will tell you all the codes step by step.

const player = "O";
const computer = "X";

let board_full = false;
let play_board = ["", "", "", "", "", "", "", "", ""];

const board_container = document.querySelector(".play-area");
const winner_statement = document.getElementById("winner");

With these variables, you’ve defined the player and computer as “O” and “X” respectively, and created an empty board to play on. The board_full variable will be used to check if the board is full and the game is over, and the play_board array will hold the state of the game. 

The board_container variable is used to select the element on the page where the Tic Tac Toe board will be rendered, and the winner_statement variable is used to select the element where the winner statement will be displayed.

check_board_complete = () => {
  let flag = true;
  play_board.forEach(element => {
    if (element != player && element != computer) {
      flag = false;
    }
  });
  board_full = flag;
};

The function is using the forEach() method to iterate over the play_board array, and it checks if each element is not equal to the player or computer. If any element is not equal to the player or computer, it sets the flag variable to false and breaks out of the loop. 

If the loop completes and the flag variable is still true, it means that all the elements are equal to the player or computer, and the board is full. Then the board_full variable is updated to reflect that the board is full.

You can use this function at the end of the player’s turn and computer’s turn, to check if the board is full and the game is over.

const check_line = (a, b, c) => {
  return (
    play_board[a] == play_board[b] &&
    play_board[b] == play_board[c] &&
    (play_board[a] == player || play_board[a] == computer)
  );
};

The function takes in 3 arguments, a, b, c, which represent the indices of the 3 cells on the board that need to be checked for a winning line.

The function uses the ternary operator to check if the values at the indices a, b, c in the play_board array are the same and not empty. If the values are the same and not empty, the function returns true, otherwise it returns false.

You can use this function in a larger function that checks for all the possible winning combinations on the board.

const check_match = () => {
  for (i = 0; i < 9; i += 3) {
    if (check_line(i, i + 1, i + 2)) {
      document.querySelector(`#block_${i}`).classList.add("win");
      document.querySelector(`#block_${i + 1}`).classList.add("win");
      document.querySelector(`#block_${i + 2}`).classList.add("win");
      return play_board[i];
    }
  }
  for (i = 0; i < 3; i++) {
    if (check_line(i, i + 3, i + 6)) {
      document.querySelector(`#block_${i}`).classList.add("win");
      document.querySelector(`#block_${i + 3}`).classList.add("win");
      document.querySelector(`#block_${i + 6}`).classList.add("win");
      return play_board[i];
    }
  }
  if (check_line(0, 4, 8)) {
    document.querySelector("#block_0").classList.add("win");
    document.querySelector("#block_4").classList.add("win");
    document.querySelector("#block_8").classList.add("win");
    return play_board[0];
  }
  if (check_line(2, 4, 6)) {
    document.querySelector("#block_2").classList.add("win");
    document.querySelector("#block_4").classList.add("win");
    document.querySelector("#block_6").classList.add("win");
    return play_board[2];
  }
  return "";
};

The check_match() function uses two for loops to check for all the possible winning combinations on the board, both horizontally and vertically. It also includes two if statements to check for the two diagonal winning combinations.

The function uses the check_line function you created earlier to check if a line is a winning line. If a winning line is found, the function highlights the winning cells by adding the “win” class to them. This class can be used in your CSS to change the appearance of the winning cells, for example by adding a different background color.

The function also returns the value of the first cell in the winning line, which should be either “X” or “O” depending on who won the game.

You can use this function in another function that checks for a win or a draw and updates the UI accordingly.

const check_for_winner = () => {
  let res = check_match()
  if (res == player) {
    winner.innerText = "Winner is player!!";
    winner.classList.add("playerWin");
    board_full = true
  } else if (res == computer) {
    winner.innerText = "Winner is computer";
    winner.classList.add("computerWin");
    board_full = true
  } else if (board_full) {
    winner.innerText = "Draw!";
    winner.classList.add("draw");
  }
};

This code looks like it’s checking for a winner in a javascript Tic Tac Toe game. The check_line function takes in 3 indices of the play_board array and checks if the values at those indices are equal to each other and if they are equal to either the player or computer. 

The check_match function uses the check_line function to check for a winner across the rows, columns, and diagonals of the Tic Tac Toe board. If a winning line is found, the check_match function adds a “win” class to the corresponding HTML elements of the Tic Tac Toe board and returns the winning player. 

The check_for_winner function calls the check_match function and checks the returned value. If the returned value is the player, it sets the winner statement to “Winner is player!!” and adds playerWin class.

const render_board = () => {
  board_container.innerHTML = ""
  play_board.forEach((e, i) => {
    board_container.innerHTML += `<div id="block_${i}" class="block" onclick="addPlayerMove(${i})">${play_board[i]}</div>`
    if (e == player || e == computer) {
      document.querySelector(`#block_${i}`).classList.add("occupied");
    }
  });
};

The render_board() function creates a grid of divs in the HTML, each one representing a cell in the Tic-Tac-Toe board. The addPlayerMove() function allows the player to make a move by clicking on a cell in the grid. 

The check_board_complete() function checks if the board is full and the check_for_winner() function checks for a winner or draw. It also uses the check_match() function to check if any winning combination is formed.

const game_loop = () => {
  render_board();
  check_board_complete();
  check_for_winner();
}

The game_loop function combines all of these functions together to create the game loop that updates the game state and renders the game board to the user. 

It calls the render_board function to render the current state of the game board to the user, check_board_complete to check if the board is full and check_for_winner which checks if there is a winner or a draw, and updates the UI accordingly.

const addPlayerMove = e => {
  if (!board_full && play_board[e] == "") {
    play_board[e] = player;
    game_loop();
    addComputerMove();
  }
};

The above code defines a Tic Tac Toe game in JavaScript that uses HTML and CSS for the game board and styling. The game’s state is maintained in the play_board array, and the game_loop function updates the state of the game, renders the board, and checks for a winner. 

The addPlayerMove function allows players to make a move by clicking on a block on the board, and the addComputerMove function allows the computer to make a move. The check_match, check_for_winner, render_board functions are also defined and used in the game loop to check for a winner or a draw, render the board and check if the game is complete.

const addComputerMove = () => {
  if (!board_full) {
    do {
      selected = Math.floor(Math.random() * 9);
    } while (play_board[selected] != "");
    play_board[selected] = computer;
    game_loop();
  }
};

Great! Your code is now complete and should be able to run a game of javascript Tic-Tac-Toe between a player and the computer. The player can make moves by clicking on the blocks on the game board, and the computer will randomly select an available space to make its move. The code also checks for a winner or a draw after each move, and updates the game board and the winner statement accordingly.

const reset_board = () => {
  play_board = ["", "", "", "", "", "", "", "", ""];
  board_full = false;
  winner.classList.remove("playerWin");
  winner.classList.remove("computerWin");
  winner.classList.remove("draw");
  winner.innerText = "";
  render_board();
};

This code defines a function called “reset_board” that sets the play_board array back to an empty array, sets the board_full variable to false, removes any classes related to winning or drawing from the winner element, sets the inner text of the winner element to an empty string, and then calls the render_board function to update the display. This function is likely intended to be used as a way to clear the game board and start a new game.

//initial render
render_board();

That’s it, you have created a complete Tic-Tac-Toe game using JavaScript. To start the game, the player can click on any of the empty blocks on the board and the computer will automatically make its move. 

The game checks for a winner or a draw after each move and updates the board accordingly. The game can also be reset by calling the reset_board() function.

Step 6: Basic design of simple Tic-Tac-Toe game with CSS

Above we enabled Tic-tac-toe in JavaScript by JavaScript. Now we need to design it with some more CSS. We know there are 9 small boxes in this game that are currently too small for us to see. So a fixed size must be defined for each box.

.block {
  display: flex;
  width: 100px;
  height: 100px;
  align-items: center;
  justify-content: center;
  font-size: 3rem;
  font-weight: bold;
  border: 3px solid black;
  transition: background 0.2s ease-in-out;
}

.block:hover {
  cursor: pointer;
  background: #0ff30f;
}

.occupied:hover {
  background: #ff3a3a;
}

.win {
  background: #0ff30f;
}

.win:hover {
  background: #0ff30f;
}

Activate Simple Tic-Tac-Toe with JavaScript

As we can see in the above image there are 9 boxes created. But we want to hide some borders here. We will use the following CSS to hide those borders.

#block_0,
#block_1,
#block_2 {
  border-top: none;
}

#block_0,
#block_3,
#block_6 {
  border-left: none;
}

#block_6,
#block_7,
#block_8 {
  border-bottom: none;
}

#block_2,
#block_5,
#block_8 {
  border-right: none;
}
.playerWin {
  color: green;
}

.computerWin {
  color: red;
}

.draw {
  color: orangered;
}

We’ll make this project(Create a Tic-Tac-Toe with HTML and JavaScript) responsive  using a small amount of our own code. Here for Responsive only headings have been resized or reduced.

@media only screen and (max-width: 600px) {

  h1 {
    font-size: 3rem;
    margin-bottom: 0.5em;
  }

  h2 {
    margin-top: 1em;
    font-size: 1.3rem;
  }
}

Create Tic Tac Toe with JavaScript

Hope from this tutorial you got to know how I made this Simple Tic-Tac-Toe JavaScript game.

Not only this but earlier I have shared more advanced game tutorials. Earlier I shared another JavaScript Tic-Tac-Toe which is basically made by Simple Code. Where you can play with two users rather than with the computer. Be sure to comment how you like this project(How to Recreate Tic-Tac-Toe in Vanilla JavaScript).

Original article source at: https://foolishdeveloper.com/

#javascript 

Pyringe: Debugger Capable Of Attaching to & Injecting Code Into Python

DISCLAIMER: This is not an official google project, this is just something I wrote while at Google.

Pyringe

What this is

Pyringe is a python debugger capable of attaching to running processes, inspecting their state and even of injecting python code into them while they're running. With pyringe, you can list threads, get tracebacks, inspect locals/globals/builtins of running functions, all without having to prepare your program for it.

What this is not

A "Google project". It's my internship project that got open-sourced. Sorry for the confusion.

What do I need?

Pyringe internally uses gdb to do a lot of its heavy lifting, so you will need a fairly recent build of gdb (version 7.4 onwards, and only if gdb was configured with --with-python). You will also need the symbols for whatever build of python you're running.
On Fedora, the package you're looking for is python-debuginfo, on Debian it's called python2.7-dbg (adjust according to version). Arch Linux users: see issue #5, Ubuntu users can only debug the python-dbg binary (see issue #19).
Having Colorama will get you output in boldface, but it's optional.

How do I get it?

Get it from the Github repo, PyPI, or via pip (pip install pyringe).

Is this Python3-friendly?

Short answer: No, sorry. Long answer:
There's three potentially different versions of python in play here:

  1. The version running pyringe
  2. The version being debugged
  3. The version of libpythonXX.so your build of gdb was linked against

2 Is currently the dealbreaker here. Cpython has changed a bit in the meantime[1], and making all features work while debugging python3 will have to take a back seat for now until the more glaring issues have been taken care of.
As for 1 and 3, the 2to3 tool may be able to handle it automatically. But then, as long as 2 hasn't been taken care of, this isn't really a use case in the first place.

[1] - For example, pendingbusy (which is used for injection) has been renamed to busy and been given a function-local scope, making it harder to interact with via gdb.

Will this work with PyPy?

Unfortunately, no. Since this makes use of some CPython internals and implementation details, only CPython is supported. If you don't know what PyPy or CPython are, you'll probably be fine.

Why not PDB?

PDB is great. Use it where applicable! But sometimes it isn't.
Like when python itself crashes, gets stuck in some C extension, or you want to inspect data without stopping a program. In such cases, PDB (and all other debuggers that run within the interpreter itself) are next to useless, and without pyringe you'd be left with having to debug using print statements. Pyringe is just quite convenient in these cases.

I injected a change to a local var into a function and it's not showing up!

This is a known limitation. Things like inject('var = 2') won't work, but inject('var[1] = 1337') should. This is because most of the time, python internally uses a fast path for looking up local variables that doesn't actually perform the dictionary lookup in locals(). In general, code you inject into processes with pyringe is very different from a normal python function call.

How do I use it?

You can start the debugger by executing python -m pyringe. Alternatively:

import pyringe
pyringe.interact()

If that reminds you of the code module, good; this is intentional.
After starting the debugger, you'll be greeted by what behaves almost like a regular python REPL.
Try the following:

==> pid:[None] #threads:[0] current thread:[None]
>>> help()
Available commands:
 attach: Attach to the process with the given pid.
 bt: Get a backtrace of the current position.
 [...]
==> pid:[None] #threads:[0] current thread:[None]
>>> attach(12679)
==> pid:[12679] #threads:[11] current thread:[140108099462912]
>>> threads()
[140108099462912, 140108107855616, 140108116248323, 140108124641024, 140108133033728, 140108224739072, 140108233131776, 140108141426432, 140108241524480, 140108249917184, 140108269324032]

The IDs you see here correspond to what threading.current_thread().ident would tell you.
All debugger functions are just regular python functions that have been exposed to the REPL, so you can do things like the following.

==> pid:[12679] #threads:[11] current thread:[140108099462912]
>>> for tid in threads():
...   if not tid % 10:
...     thread(tid)
...     bt()
... 
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 524, in __bootstrap
    self.__bootstrap_inner()
  File "/usr/lib/python2.7/threading.py", line 551, in __bootstrap_inner
    self.run()
  File "/usr/lib/python2.7/threading.py", line 504, in run
    self.__target(*self.__args, **self.__kwargs)
  File "./test.py", line 46, in Idle
    Thread_2_Func(1)
  File "./test.py", line 40, in Wait
    time.sleep(n)
==> pid:[12679] #threads:[11] current thread:[140108241524480]
>>> 

You can access the inferior's locals and inspect them like so:

==> pid:[12679] #threads:[11] current thread:[140108241524480]
>>> inflocals()
{'a': <proxy of A object at remote 0x1d9b290>, 'LOL': 'success!', 'b': <proxy of B object at remote 0x1d988c0>, 'n': 1}
==> pid:[12679] #threads:[11] current thread:[140108241524480]
>>> p('a')
<proxy of A object at remote 0x1d9b290>
==> pid:[12679] #threads:[11] current thread:[140108241524480]
>>> p('a').attr
'Some_magic_string'
==> pid:[12679] #threads:[11] current thread:[140108241524480]
>>> 

And sure enough, the definition of a's class reads:

class Example(object):
  cl_attr = False
  def __init__(self):
    self.attr = 'Some_magic_string'

There's limits to how far this proxying of objects goes, and everything that isn't trivial data will show up as strings (like '<function at remote 0x1d957d0>').
You can inject python code into running programs. Of course, there are caveats but... see for yourself:

==> pid:[12679] #threads:[11] current thread:[140108241524480]
>>> inject('import threading')
==> pid:[12679] #threads:[11] current thread:[140108241524480]
>>> inject('print threading.current_thread().ident')
==> pid:[12679] #threads:[11] current thread:[140108241524480]
>>> 

The output of my program in this case reads:

140108241524480

If you need additional pointers, just try using python's help (pyhelp() in the debugger) on debugger commands.

Author: google
Source Code: https://github.com/google/pyringe
License: Apache-2.0 License

#python 

Libraries for Debugging Code in Popular Python

In this Python article, let's learn about Debugging Tools: Libraries for Debugging Code in Popular Python

Table of contents:

  • pdb-like Debugger
    • ipdb - IPython-enabled pdb.
    • pdb++ - Another drop-in replacement for pdb.
    • pudb - A full-screen, console-based Python debugger.
    • wdb - An improbable web debugger through WebSockets.
  • Tracing
    • lptrace - strace for Python programs.
    • manhole - Debugging UNIX socket connections and present the stacktraces for all threads and an interactive prompt.
    • pyringe - Debugger capable of attaching to and injecting code into Python processes.
    • python-hunter - A flexible code tracing toolkit.
  • Profiler
    • line_profiler - Line-by-line profiling.
    • memory_profiler - Monitor Memory usage of Python code.
    • py-spy - A sampling profiler for Python programs. Written in Rust.
    • pyflame - A ptracing profiler For Python.
    • vprof - Visual Python profiler.
  • Others
    • django-debug-toolbar - Display various debug information for Django.
    • django-devserver - A drop-in replacement for Django's runserver.
    • flask-debugtoolbar - A port of the django-debug-toolbar to flask.
    • icecream - Inspect variables, expressions, and program execution with a single, simple function call.
    • pyelftools - Parsing and analyzing ELF files and DWARF debugging information.

 

What is a debugging tool?

A debugger is a software tool that can help the software development process by identifying coding errors at various stages of the operating system or application development. Some debuggers will analyze a test run to see what lines of code were not executed.

Debugger for Python programs with a graphical user interface. It uses bdb (part of stdlib) but adds a GUI and has some powerful features like object browser, windows for variables, classes, functions, exceptions, stack, conditional breakpoints, etc.


Libraries for Debugging Code in Popular Python

  1. IPython pdb

ipdb exports functions to access the IPython debugger, which features tab completion, syntax highlighting, better tracebacks, better introspection with the same interface as the pdb module.

Example usage:

import ipdb
ipdb.set_trace()
ipdb.set_trace(context=5)  # will show five lines of code
                           # instead of the default three lines
                           # or you can set it via IPDB_CONTEXT_SIZE env variable
                           # or setup.cfg file
ipdb.pm()
ipdb.run('x[0] = 3')
result = ipdb.runcall(function, arg0, arg1, kwarg='foo')
result = ipdb.runeval('f(1,2) - 3')

Arguments for set_trace

The set_trace function accepts context which will show as many lines of code as defined, and cond, which accepts boolean values (such as abc == 17) and will start ipdb's interface whenever cond equals to True.

Using configuration file

It's possible to set up context using a .ipdb file on your home folder, setup.cfg or pyproject.toml on your project folder. You can also set your file location via env var $IPDB_CONFIG. Your environment variable has priority over the home configuration file, which in turn has priority over the setup config file. Currently, only context setting is available.

A valid setup.cfg is as follows

[ipdb]
context=5

A valid .ipdb is as follows

context=5

A valid pyproject.toml is as follows

[tool.ipdb]
context=5

The post-mortem function, ipdb.pm(), is equivalent to the magic function %debug.

View on GitHub


2.  pdb++

pdb++, a drop-in replacement for pdb (the Python debugger)

What is it?

This module is an extension of the pdb module of the standard library. It is meant to be fully compatible with its predecessor, yet it introduces a number of new features to make your debugging experience as nice as possible.

https://user-images.githubusercontent.com/412005/64484794-2f373380-d20f-11e9-9f04-e1dabf113c6f.png

pdb++ features include:

  • colorful TAB completion of Python expressions (through fancycompleter)
  • optional syntax highlighting of code listings (through Pygments)
  • sticky mode
  • several new commands to be used from the interactive (Pdb++) prompt
  • smart command parsing (hint: have you ever typed r or c at the prompt to print the value of some variable?)
  • additional convenience functions in the pdb module, to be used from your program

pdb++ is meant to be a drop-in replacement for pdb. If you find some unexpected behavior, please report it as a bug.

Installation

Since pdb++ is not a valid package name the package is named pdbpp:

$ pip install pdbpp

pdb++ is also available via conda:

$ conda install -c conda-forge pdbpp

Alternatively, you can just put pdb.py somewhere inside your PYTHONPATH.

View on GitHub


3.  PuDB

Its goal is to provide all the niceties of modern GUI-based debuggers in a more lightweight and keyboard-friendly package. PuDB allows you to debug code right where you write and test it--in a terminal.

Here are some screenshots:

Light theme

  • doc/images/pudb-screenshot-light.png

Dark theme

  • doc/images/pudb-screenshot-dark.png

View on GitHub


4.  wdb

An improbable web debugger through WebSockets

wdb is a full featured web debugger based on a client-server architecture.

The wdb server which is responsible of managing debugging instances along with browser connections (through websockets) is based on Tornado. The wdb clients allow step by step debugging, in-program python code execution, code edition (based on CodeMirror) setting breakpoints...

Due to this architecture, all of this is fully compatible with multithread and multiprocess programs.

wdb works with python 2 (2.6, 2.7), python 3 (3.2, 3.3, 3.4, 3.5) and pypy. Even better, it is possible to debug a python 2 program with a wdb server running on python 3 and vice-versa or debug a program running on a computer with a debugging server running on another computer inside a web page on a third computer!

Even betterer, it is now possible to pause a currently running python process/thread using code injection from the web interface. (This requires gdb and ptrace enabled)

In other words it's a very enhanced version of pdb directly in your browser with nice features.

Installation:

Global installation:

    $ pip install wdb.server

In virtualenv or with a different python installation:

    $ pip install wdb

(You must have the server installed and running)

View on GitHub


5.  lptrace

lptrace is strace for Python programs. It lets you see in real-time what functions a Python program is running. It's particularly useful to debug weird issues on production.

For example, let's debug a non-trivial program, the Python SimpleHTTPServer. First, let's run the server:

vagrant@precise32:/vagrant$ python -m SimpleHTTPServer 8080 &
[1] 1818
vagrant@precise32:/vagrant$ Serving HTTP on 0.0.0.0 port 8080 ...

Now let's connect lptrace to it:

vagrant@precise32:/vagrant$ sudo python lptrace -p 1818
...
fileno (/usr/lib/python2.7/SocketServer.py:438)
meth (/usr/lib/python2.7/socket.py:223)

fileno (/usr/lib/python2.7/SocketServer.py:438)
meth (/usr/lib/python2.7/socket.py:223)

_handle_request_noblock (/usr/lib/python2.7/SocketServer.py:271)
get_request (/usr/lib/python2.7/SocketServer.py:446)
accept (/usr/lib/python2.7/socket.py:201)
__init__ (/usr/lib/python2.7/socket.py:185)
verify_request (/usr/lib/python2.7/SocketServer.py:296)
process_request (/usr/lib/python2.7/SocketServer.py:304)
finish_request (/usr/lib/python2.7/SocketServer.py:321)
__init__ (/usr/lib/python2.7/SocketServer.py:632)
setup (/usr/lib/python2.7/SocketServer.py:681)
makefile (/usr/lib/python2.7/socket.py:212)
__init__ (/usr/lib/python2.7/socket.py:246)
makefile (/usr/lib/python2.7/socket.py:212)
__init__ (/usr/lib/python2.7/socket.py:246)
handle (/usr/lib/python2.7/BaseHTTPServer.py:336)
handle_one_request (/usr/lib/python2.7/BaseHTTPServer.py:301)
^CReceived Ctrl-C, quitting
vagrant@precise32:/vagrant$

You can see that the server is handling the request in real time! After pressing Ctrl-C, the trace is removed and the program execution resumes normally.

View on GitHub


6.  python-manhole

Debugging manhole for python applications.

Manhole is in-process service that will accept unix domain socket connections and present the stacktraces for all threads and an interactive prompt. It can either work as a python daemon thread waiting for connections at all times or a signal handler (stopping your application and waiting for a connection).

Access to the socket is restricted to the application's effective user id or root.

This is just like Twisted's manhole. It's simpler (no dependencies), it only runs on Unix domain sockets (in contrast to Twisted's manhole which can run on telnet or ssh) and it integrates well with various types of applications.

Usage

Install it:

pip install manhole

You can put this in your django settings, wsgi app file, some module that's always imported early etc:

import manhole
manhole.install() # this will start the daemon thread

# and now you start your app, eg: server.serve_forever()

Now in a shell you can do either of these:

netcat -U /tmp/manhole-1234
socat - unix-connect:/tmp/manhole-1234
socat readline unix-connect:/tmp/manhole-1234

Socat with readline is best (history, editing etc). If your socat doesn't have readline try this.

Sample output:

$ nc -U /tmp/manhole-1234

Python 2.7.3 (default, Apr 10 2013, 06:20:15)
[GCC 4.6.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
(InteractiveConsole)
>>> dir()
['__builtins__', 'dump_stacktraces', 'os', 'socket', 'sys', 'traceback']
>>> print 'foobar'
foobar

View on GitHub


7.  Pyringe

Pyringe is a python debugger capable of attaching to running processes, inspecting their state and even of injecting python code into them while they're running. With pyringe, you can list threads, get tracebacks, inspect locals/globals/builtins of running functions, all without having to prepare your program for it.

How do I use it?

You can start the debugger by executing python -m pyringe. Alternatively:

import pyringe
pyringe.interact()

If that reminds you of the code module, good; this is intentional.
After starting the debugger, you'll be greeted by what behaves almost like a regular python REPL.
Try the following:

==> pid:[None] #threads:[0] current thread:[None]
>>> help()
Available commands:
 attach: Attach to the process with the given pid.
 bt: Get a backtrace of the current position.
 [...]
==> pid:[None] #threads:[0] current thread:[None]
>>> attach(12679)
==> pid:[12679] #threads:[11] current thread:[140108099462912]
>>> threads()
[140108099462912, 140108107855616, 140108116248323, 140108124641024, 140108133033728, 140108224739072, 140108233131776, 140108141426432, 140108241524480, 140108249917184, 140108269324032]

The IDs you see here correspond to what threading.current_thread().ident would tell you.
All debugger functions are just regular python functions that have been exposed to the REPL, so you can do things like the following.

==> pid:[12679] #threads:[11] current thread:[140108099462912]
>>> for tid in threads():
...   if not tid % 10:
...     thread(tid)
...     bt()
... 
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 524, in __bootstrap
    self.__bootstrap_inner()
  File "/usr/lib/python2.7/threading.py", line 551, in __bootstrap_inner
    self.run()
  File "/usr/lib/python2.7/threading.py", line 504, in run
    self.__target(*self.__args, **self.__kwargs)
  File "./test.py", line 46, in Idle
    Thread_2_Func(1)
  File "./test.py", line 40, in Wait
    time.sleep(n)
==> pid:[12679] #threads:[11] current thread:[140108241524480]
>>> 

You can access the inferior's locals and inspect them like so:

==> pid:[12679] #threads:[11] current thread:[140108241524480]
>>> inflocals()
{'a': <proxy of A object at remote 0x1d9b290>, 'LOL': 'success!', 'b': <proxy of B object at remote 0x1d988c0>, 'n': 1}
==> pid:[12679] #threads:[11] current thread:[140108241524480]
>>> p('a')
<proxy of A object at remote 0x1d9b290>
==> pid:[12679] #threads:[11] current thread:[140108241524480]
>>> p('a').attr
'Some_magic_string'
==> pid:[12679] #threads:[11] current thread:[140108241524480]
>>> 

And sure enough, the definition of a's class reads:

class Example(object):
  cl_attr = False
  def __init__(self):
    self.attr = 'Some_magic_string'

There's limits to how far this proxying of objects goes, and everything that isn't trivial data will show up as strings (like '<function at remote 0x1d957d0>').

View on GitHub


8.  python-hunter

Hunter is a flexible code tracing toolkit, not for measuring coverage, but for debugging, logging, inspection and other nefarious purposes. It has a simple Python API, a convenient terminal API and a CLI tool to attach to processes.

Installation

pip install hunter

Documentation

https://python-hunter.readthedocs.io/

Getting started

Basic use involves passing various filters to the trace option. An example:

import hunter
hunter.trace(module='posixpath', action=hunter.CallPrinter)

import os
os.path.join('a', 'b')

That would result in:

>>> os.path.join('a', 'b')
         /usr/lib/python3.6/posixpath.py:75    call      => join(a='a')
         /usr/lib/python3.6/posixpath.py:80    line         a = os.fspath(a)
         /usr/lib/python3.6/posixpath.py:81    line         sep = _get_sep(a)
         /usr/lib/python3.6/posixpath.py:41    call         => _get_sep(path='a')
         /usr/lib/python3.6/posixpath.py:42    line            if isinstance(path, bytes):
         /usr/lib/python3.6/posixpath.py:45    line            return '/'
         /usr/lib/python3.6/posixpath.py:45    return       <= _get_sep: '/'
         /usr/lib/python3.6/posixpath.py:82    line         path = a
         /usr/lib/python3.6/posixpath.py:83    line         try:
         /usr/lib/python3.6/posixpath.py:84    line         if not p:
         /usr/lib/python3.6/posixpath.py:86    line         for b in map(os.fspath, p):
         /usr/lib/python3.6/posixpath.py:87    line         if b.startswith(sep):
         /usr/lib/python3.6/posixpath.py:89    line         elif not path or path.endswith(sep):
         /usr/lib/python3.6/posixpath.py:92    line         path += sep + b
         /usr/lib/python3.6/posixpath.py:86    line         for b in map(os.fspath, p):
         /usr/lib/python3.6/posixpath.py:96    line         return path
         /usr/lib/python3.6/posixpath.py:96    return    <= join: 'a/b'
'a/b'

In a terminal it would look like:

https://raw.githubusercontent.com/ionelmc/python-hunter/master/docs/code-trace.png

Another useful scenario is to ignore all standard modules and force colors to make them stay even if the output is redirected to a file.

import hunter
hunter.trace(stdlib=False, action=hunter.CallPrinter(force_colors=True))

View on GitHub


9.  line_profiler

line_profiler is a module for doing line-by-line profiling of functions. kernprof is a convenient script for running either line_profiler or the Python standard library's cProfile or profile modules, depending on what is available.

Installation

Note: As of version 2.1.2, pip install line_profiler does not work. Please install as follows until it is fixed in the next release:

git clone https://github.com/rkern/line_profiler.git
find line_profiler -name '*.pyx' -exec cython {} \;
cd line_profiler
pip install . --user

Releases of line_profiler can be installed using pip:

$ pip install line_profiler

Source releases and any binaries can be downloaded from the PyPI link.

http://pypi.python.org/pypi/line_profiler

To check out the development sources, you can use Git:

$ git clone https://github.com/rkern/line_profiler.git

You may also download source tarballs of any snapshot from that URL.

Source releases will require a C compiler in order to build line_profiler. In addition, git checkouts will also require Cython >= 0.10. Source releases on PyPI should contain the pregenerated C sources, so Cython should not be required in that case.

kernprof is a single-file pure Python script and does not require a compiler. If you wish to use it to run cProfile and not line-by-line profiling, you may copy it to a directory on your PATH manually and avoid trying to build any C extensions.

View on GitHub


10.  Memory Profiler

This is a python module for monitoring memory consumption of a process as well as line-by-line analysis of memory consumption for python programs. It is a pure python module which depends on the psutil module.

Installation

To install through easy_install or pip:

$ easy_install -U memory_profiler # pip install -U memory_profiler

To install from source, download the package, extract and type:

$ python setup.py install

Usage

line-by-line memory usage

The line-by-line memory usage mode is used much in the same way of the line_profiler: first decorate the function you would like to profile with @profile and then run the script with a special script (in this case with specific arguments to the Python interpreter).

In the following example, we create a simple function my_func that allocates lists a, b and then deletes b:

@profile
def my_func():
    a = [1] * (10 ** 6)
    b = [2] * (2 * 10 ** 7)
    del b
    return a

if __name__ == '__main__':
    my_func()

Execute the code passing the option -m memory_profiler to the python interpreter to load the memory_profiler module and print to stdout the line-by-line analysis. If the file name was example.py, this would result in:

$ python -m memory_profiler example.py

Output will follow:

Line #    Mem usage  Increment   Line Contents
==============================================
     3                           @profile
     4      5.97 MB    0.00 MB   def my_func():
     5     13.61 MB    7.64 MB       a = [1] * (10 ** 6)
     6    166.20 MB  152.59 MB       b = [2] * (2 * 10 ** 7)
     7     13.61 MB -152.59 MB       del b
     8     13.61 MB    0.00 MB       return a

The first column represents the line number of the code that has been profiled, the second column (Mem usage) the memory usage of the Python interpreter after that line has been executed. The third column (Increment) represents the difference in memory of the current line with respect to the last one. The last column (Line Contents) prints the code that has been profiled.

View on GitHub


11.  py-spy

py-spy is a sampling profiler for Python programs. It lets you visualize what your Python program is spending time on without restarting the program or modifying the code in any way. py-spy is extremely low overhead: it is written in Rust for speed and doesn't run in the same process as the profiled Python program. This means py-spy is safe to use against production Python code.

py-spy works on Linux, OSX, Windows and FreeBSD, and supports profiling all recent versions of the CPython interpreter (versions 2.3-2.7 and 3.3-3.10).

Installation

Prebuilt binary wheels can be installed from PyPI with:

pip install py-spy

You can also download prebuilt binaries from the GitHub Releases Page.

If you're a Rust user, py-spy can also be installed with: cargo install py-spy.

On macOS, py-spy is in Homebrew and can be installed with brew install py-spy.

On Arch Linux, py-spy is in AUR and can be installed with yay -S py-spy.

On Alpine Linux, py-spy is in testing repository and can be installed with apk add py-spy --update-cache --repository http://dl-3.alpinelinux.org/alpine/edge/testing/ --allow-untrusted.

Usage

py-spy works from the command line and takes either the PID of the program you want to sample from or the command line of the python program you want to run. py-spy has three subcommands record, top and dump:

record

py-spy supports recording profiles to a file using the record command. For example, you can generate a flame graph of your python process by going:

py-spy record -o profile.svg --pid 12345
# OR
py-spy record -o profile.svg -- python myprogram.py

View on GitHub


12.  Pyflame

Pyflame is a high performance profiling tool that generates flame graphs for Python. Pyflame is implemented in C++, and uses the Linux ptrace(2) system call to collect profiling information. It can take snapshots of the Python call stack without explicit instrumentation, meaning you can profile a program without modifying its source code. Pyflame is capable of profiling embedded Python interpreters like uWSGI. It fully supports profiling multi-threaded Python programs.

Pyflame usually introduces significantly less overhead than the builtin profile (or cProfile) modules, and emits richer profiling data. The profiling overhead is low enough that you can use it to profile live processes in production.

Quickstart

Building And Installing

For Debian/Ubuntu, install the following:

# Install build dependencies on Debian or Ubuntu.
sudo apt-get install autoconf automake autotools-dev g++ pkg-config python-dev python3-dev libtool make

Once you have the build dependencies installed:

./autogen.sh
./configure
make

The make command will produce an executable at src/pyflame that you can run and use.

Optionally, if you have virtualenv installed, you can test the executable you produced using make check.

Using Pyflame

The full documentation for using Pyflame is here. But here's a quick guide:

# Attach to PID 12345 and profile it for 1 second
pyflame -p 12345

# Attach to PID 768 and profile it for 5 seconds, sampling every 0.01 seconds
pyflame -s 5 -r 0.01 -p 768

# Run py.test against tests/, emitting sample data to prof.txt
pyflame -o prof.txt -t py.test tests/

In all of these cases you will get flame graph data on stdout (or to a file if you used -o). This data is in the format expected by flamegraph.pl, which you can find here.

View on GitHub


13.  vprof

vprof is a Python package providing rich and interactive visualizations for various Python program characteristics such as running time and memory usage. It supports Python 3.4+ and distributed under BSD license.

The project is in active development and some of its features might not work as expected.

Installation

vprof can be installed from PyPI

pip install vprof

To build vprof from sources, clone this repository and execute

python3 setup.py deps_install && python3 setup.py build_ui && python3 setup.py install

To install just vprof dependencies, run

python3 setup.py deps_install

Usage

vprof -c <config> <src>

<config> is a combination of supported modes:

  • c - CPU flame graph ⚠️ Not available for windows #62

Shows CPU flame graph for <src>.

  • p - profiler

Runs built-in Python profiler on <src> and displays results.

  • m - memory graph

Shows objects that are tracked by CPython GC and left in memory after code execution. Also shows process memory usage after execution of each line of <src>.

  • h - code heatmap

Displays all executed code of <src> with line run times and execution counts.

View on GitHub


14.  Django Debug Toolbar

The Django Debug Toolbar is a configurable set of panels that display various debug information about the current request/response and when clicked, display more details about the panel's content.


Here's a screenshot of the toolbar in action:

Django Debug Toolbar screenshot

In addition to the built-in panels, a number of third-party panels are contributed by the community.

The current stable version of the Debug Toolbar is 3.6.0. It works on Django ≥ 3.2.4.

View on GitHub


15.  django-devserver

A drop in replacement for Django's built-in runserver command. Features include:

  • An extendable interface for handling things such as real-time logging.
  • Integration with the werkzeug interactive debugger.
  • Threaded (default) and multi-process development servers.
  • Ability to specify a WSGI application as your target environment.

Note

django-devserver works on Django 1.3 and newer

Installation

To install the latest stable version:

pip install git+git://github.com/dcramer/django-devserver#egg=django-devserver

django-devserver has some optional dependancies, which we highly recommend installing.

  • pip install sqlparse -- pretty SQL formatting
  • pip install werkzeug -- interactive debugger
  • pip install guppy -- tracks memory usage (required for MemoryUseModule)
  • pip install line_profiler -- does line-by-line profiling (required for LineProfilerModule)

You will need to include devserver in your INSTALLED_APPS:

INSTALLED_APPS = (
    ...
    'devserver',
)

If you're using django.contrib.staticfiles or any other apps with management command runserver, make sure to put devserver above any of them (or below, for Django<1.7). Otherwise devserver will log an error, but it will fail to work properly.

View on GitHub


16.  Flask Debug-toolbar

This is a port of the excellent django-debug-toolbar for Flask applications.

Installation

Installing is simple with pip:

$ pip install flask-debugtoolbar

Usage

Setting up the debug toolbar is simple:

from flask import Flask
from flask_debugtoolbar import DebugToolbarExtension

app = Flask(__name__)

# the toolbar is only enabled in debug mode:
app.debug = True

# set a 'SECRET_KEY' to enable the Flask session cookies
app.config['SECRET_KEY'] = '<replace with a secret key>'

toolbar = DebugToolbarExtension(app)

The toolbar will automatically be injected into Jinja templates when debug mode is on. In production, setting app.debug = False will disable the toolbar.

View on GitHub


17.  IceCream

Do you ever use print() or log() to debug your code? Of course you do. IceCream, or ic for short, makes print debugging a little sweeter.

ic() is like print(), but better:

  1. It prints both expressions/variable names and their values.
  2. It's 40% faster to type.
  3. Data structures are pretty printed.
  4. Output is syntax highlighted.
  5. It optionally includes program context: filename, line number, and parent function.

IceCream is well tested, permissively licensed, and supports Python 2, Python 3, PyPy2, and PyPy3. (Python 3.11 support is forthcoming.)

Inspect Variables

Have you ever printed variables or expressions to debug your program? If you've ever typed something like

print(foo('123'))

or the more thorough

print("foo('123')", foo('123'))

then ic() will put a smile on your face. With arguments, ic() inspects itself and prints both its own arguments and the values of those arguments.

from icecream import ic

def foo(i):
    return i + 333

ic(foo(123))

Prints

ic| foo(123): 456

Similarly,

d = {'key': {1: 'one'}}
ic(d['key'][1])

class klass():
    attr = 'yep'
ic(klass.attr)

Prints

ic| d['key'][1]: 'one'
ic| klass.attr: 'yep'

Just give ic() a variable or expression and you're done. Easy.

View on GitHub


18.  pyelftools

pyelftools is a pure-Python library for parsing and analyzing ELF files and DWARF debugging information. See the User's guide for more details.

Pre-requisites

As a user of pyelftools, one only needs Python 3 to run. For hacking on pyelftools the requirements are a bit more strict, please see the hacking guide.

Installing

pyelftools can be installed from PyPI (Python package index):

> pip install pyelftools

Alternatively, you can download the source distribution for the most recent and historic versions from the Downloads tab on the pyelftools project page (by going to Tags). Then, you can install from source, as usual:

> python setup.py install

Since pyelftools is a work in progress, it's recommended to have the most recent version of the code. This can be done by downloading the master zip file or just cloning the Git repository.

Since pyelftools has no external dependencies, it's also easy to use it without installing, by locally adjusting PYTHONPATH.

View on GitHub


FAQ about Debugging Tools python

  • How many types of debugging are in Python?

Debugging in any programming language typically involves two types of errors: syntax or logical. Syntax errors are those where the programming language commands are not interpreted by the compiler or interpreter because of a problem with how the program is written.

  • Best Debugging Tools include:

Chrome DevTools, Progress Telerik Fiddler, GDB (GNU Debugger), Data Display Debugger, SonarLint, Froglogic Squish, and TotalView HPC Debugging Software.

  • Why is it called debugging?

The terms "bug" and "debugging" are popularly attributed to Admiral Grace Hopper in the 1940s. While she was working on a Mark II computer at Harvard University, her associates discovered a moth stuck in a relay and thereby impeding operation, whereupon she remarked that they were "debugging" the system.

  • Why do we need debugging?

Debugging is important because it allows software engineers and developers to fix errors in a program before releasing it to the public. It's a complementary process to testing, which involves learning how an error affects a program overall.


Related videos:

Python Tutorial - Introduction to DEBUGGING


Related posts:

#python 

Lawrence  Lesch

Lawrence Lesch

1662107520

Superdom: Better and Simpler ES6 DOM Manipulation

Superdom

You have dom. It has all the DOM virtually within it. Use that power:

// Fetch all the page links
let links = dom.a.href;

// Links open in a new tab
dom.a.target = '_blank';

Only for modern browsers

Getting started

Simply use the CDN via unpkg.com:

<script src="https://unpkg.com/superdom@1"></script>

Or use npm or bower:

npm|bower install superdom --save

Select

It always returns an array with the matched elements. Get all the elements that match the selector:

// Simple element selector into an array
let allLinks = dom.a;

// Loop straight on the selection
dom.a.forEach(link => { ... });

// Combined selector
let importantLinks = dom['a.important'];

There are also some predetermined elements, such as id, class and attr:

// Select HTML Elements by id:
let main = dom.id.main;

// by class:
let buttons = dom.class.button;

// or by attribute:
let targeted = dom.attr.target;
let targeted = dom.attr['target="_blank"'];

Generate

Use it as a function or a tagged template literal to generate DOM fragments:

// Not a typo; tagged template literals
let link = dom`<a href="https://google.com/">Google</a>`;

// It is the same as
let link = dom('<a href="https://google.com/">Google</a>');

Delete elements

Delete a piece of the DOM

// Delete all of the elements with the class .google
delete dom.class.google;   // Is this an ad-block rule?

Attributes

You can easily manipulate attributes right from the dom node. There are some aliases that share the syntax of the attributes such as html and text (aliases for innerHTML and textContent). There are others that travel through the dom such as parent (alias for parentNode) and children. Finally, class behaves differently as explained below.

Get attributes

The fetching will always return an array with the element for each of the matched nodes (or undefined if not there):

// Retrieve all the urls from the page
let urls = dom.a.href;     // #attr-list
  // ['https://google.com', 'https://facebook.com/', ...]

// Get an array of the h2 contents (alias of innerHTML)
let h2s = dom.h2.html;     // #attr-alias
  // ['Level 2 header', 'Another level 2 header', ...]

// Get whether any of the attributes has the value "_blank"
let hasBlank = dom.class.cta.target._blank;    // #attr-value
  // true/false

You also use these:

  • html (alias of innerHTML): retrieve a list of the htmls
  • text (alias of textContent): retrieve a list of the htmls
  • parent (alias of parentNode): travel up one level
  • children: travel down one level

Set attributes

// Set target="_blank" to all links
dom.a.target = '_blank';     // #attr-set
dom.class.tableofcontents.html = `
  <ul class="tableofcontents">
    ${dom.h2.map(h2 => `
      <li>
        <a href="#${h2.id}">
          ${h2.innerHTML}
        </a>
      </li>
    `).join('')}
  </ul>
`;

Remove an attribute

To delete an attribute use the delete keyword:

// Remove all urls from the page
delete dom.a.href;

// Remove all ids
delete dom.a.id;

Classes

It provides an easy way to manipulate the classes.

Get classes

To retrieve whether a particular class is present or not:

// Get an array with true/false for a single class
let isTest = dom.a.class.test;     // #class-one

For a general method to retrieve all classes you can do:

// Get a list of the classes of each matched element
let arrays = dom.a.class;     // #class-arrays
  // [['important'], ['button', 'cta'], ...]

// If you want a plain list with all of the classes:
let flatten = dom.a.class._flat;     // #class-flat
  // ['important', 'button', 'cta', ...]

// And if you just want an string with space-separated classes:
let text = dom.a.class._text;     // #class-text
  // 'important button cta ...'

Add a class

// Add the class 'test' (different ways)
dom.a.class.test = true;    // #class-make-true
dom.a.class = 'test';       // #class-push

Remove a class

// Remove the class 'test'
dom.a.class.test = false;    // #class-make-false

Manipulate

Did we say it returns a simple array?

dom.a.forEach(link => link.innerHTML = 'I am a link');

But what an interesting array it is; indeed we are also proxy'ing it so you can manipulate its sub-elements straight from the selector:

// Replace all of the link's html with 'I am a link'
dom.a.html = 'I am a link';

Of course we might want to manipulate them dynamically depending on the current value. Just pass it a function:

// Append ' ^_^' to all of the links in the page
dom.a.html = html => html + ' ^_^';

// Same as this:
dom.a.forEach(link => link.innerHTML = link.innerHTML + ' ^_^');

Note: this won't work dom.a.html += ' ^_^'; for more than 1 match (for reasons)

Or get into genetics to manipulate the attributes:

dom.a.attr.target = '_blank';

// Only to external sites:
let isOwnPage = el => /^https?\:\/\/mypage\.com/.test(el.getAttribute('href'));
dom.a.attr.target = (prev, i, element) => isOwnPage(element) ? '' : '_blank';

Events

You can also handle and trigger events:

// Handle click events for all <a>
dom.a.on.click = e => ...;

// Trigger click event for all <a>
dom.a.trigger.click;

Testing

We are using Jest as a Grunt task for testing. Install Jest and run in the terminal:

grunt watch

Download Details:

Author: franciscop
Source Code: https://github.com/franciscop/superdom 
License: MIT license

#javascript #es6 #dom 

Yashi Tyagi

1617449307

CA Classes - Best CA Classes Online

Chartered Accountancy course requires mental focus & discipline, coaching for CA Foundation, CA Inter and CA Finals are omnipresent, and some of the best faculty’s classes have moved online, in this blog, we are going to give the best way to find online videos lectures, various online websites provide the CA lectures, Smartnstudy one of the best site to CA preparation, here all faculty’s video lecture available.

check here : ca classes

#ca classes online #ca classes in delhi #ca classes app #ca pendrive classes #ca google drive classes #best ca classes online