Javascript Tutorial - Safer Coding by using JSLint

What is a linter?

Linters have been around for a long time and probably exist in one shape or form for all languages. A linter is basically a parser that parses your code and looks for mistakes. It’s a great way to save time, maintain quality and write safer code. You can plug linters in to your code editor or copy-past your code to a linting tool. Lint-ing your code is a great thing to do no matter what language you code with. You can even lint HTML, CSS and JSON. There are many different types, but here I will focus on the four most popular JavaScript linters.

Workflow comparison

Example workflow WITHOUT linter

1. Write some code
2. Save your code
3. Refresh the page and wait for the page to load
4. The inspector found an error
5. You inspect the error and it says something like… “Uncaught SyntaxError: Unexpected identifier on line 43 file…”
6. You think “that’s kind of a cryptic message”. You return to the code to see what’s actually causing the problem on line 43
7. Ah, you missed a comma between your variable declarations
8. You add the comma… var variable1 = 1, variable2 = 2;
9. Then you save the project and walk yourself through the whole process again, thinking “wow, this is a bit time consuming. I really hope I didn’t miss a comma somewhere else”

Example workflow WITH linter

1. Write code. In the meantime the linter tells you about your syntax errors.
2. You fix your mistakes
3. Save your code
4. You smile and think “wow, this is the future”

#javascript #jslint

What is GEEK

Buddha Community

How to create a calculator using javascript - Pure JS tutorials |Web Tutorials

In this video I will tell you How to create a calculator using javascript very easily.

#how to build a simple calculator in javascript #how to create simple calculator using javascript #javascript calculator tutorial #javascript birthday calculator #calculator using javascript and html

Guidelines for Java Code Reviews

Get a jump-start on your next code review session with this list.

Having another pair of eyes scan your code is always useful and helps you spot mistakes before you break production. You need not be an expert to review someone’s code. Some experience with the programming language and a review checklist should help you get started. We’ve put together a list of things you should keep in mind when you’re reviewing Java code. Read on!

1. Follow Java Code Conventions

2. Replace Imperative Code With Lambdas and Streams

3. Beware of the NullPointerException

4. Directly Assigning References From Client Code to a Field

5. Handle Exceptions With Care

…

#java #code quality #java tutorial #code analysis #code reviews #code review tips #code analysis tools #java tutorial for beginners #java code review

Static Code Analysis: What It Is? How to Use It?

Static code analysis refers to the technique of approximating the runtime behavior of a program. In other words, it is the process of predicting the output of a program without actually executing it.

Lately, however, the term “Static Code Analysis” is more commonly used to refer to one of the applications of this technique rather than the technique itself — program comprehension — understanding the program and detecting issues in it (anything from syntax errors to type mismatches, performance hogs likely bugs, security loopholes, etc.). This is the usage we’d be referring to throughout this post.

“The refinement of techniques for the prompt discovery of error serves as well as any other as a hallmark of what we mean by science.”

• J. Robert Oppenheimer

Outline

We cover a lot of ground in this post. The aim is to build an understanding of static code analysis and to equip you with the basic theory, and the right tools so that you can write analyzers on your own.

We start our journey with laying down the essential parts of the pipeline which a compiler follows to understand what a piece of code does. We learn where to tap points in this pipeline to plug in our analyzers and extract meaningful information. In the latter half, we get our feet wet, and write four such static analyzers, completely from scratch, in Python.

Note that although the ideas here are discussed in light of Python, static code analyzers across all programming languages are carved out along similar lines. We chose Python because of the availability of an easy to use ast module, and wide adoption of the language itself.

How does it all work?

Before a computer can finally “understand” and execute a piece of code, it goes through a series of complicated transformations:

As you can see in the diagram (go ahead, zoom it!), the static analyzers feed on the output of these stages. To be able to better understand the static analysis techniques, let’s look at each of these steps in some more detail:

Scanning

The first thing that a compiler does when trying to understand a piece of code is to break it down into smaller chunks, also known as tokens. Tokens are akin to what words are in a language.

A token might consist of either a single character, like (, or literals (like integers, strings, e.g., 7, Bob, etc.), or reserved keywords of that language (e.g, def in Python). Characters which do not contribute towards the semantics of a program, like trailing whitespace, comments, etc. are often discarded by the scanner.

Python provides the tokenize module in its standard library to let you play around with tokens:

Python

1

import io

2

import tokenize

3

4

code = b"color = input('Enter your favourite color: ')"

5

6

for token in tokenize.tokenize(io.BytesIO(code).readline):

7

    print(token)

Python

1

TokenInfo(type=62 (ENCODING),  string='utf-8')

2

TokenInfo(type=1  (NAME),      string='color')

3

TokenInfo(type=54 (OP),        string='=')

4

TokenInfo(type=1  (NAME),      string='input')

5

TokenInfo(type=54 (OP),        string='(')

6

TokenInfo(type=3  (STRING),    string="'Enter your favourite color: '")

7

TokenInfo(type=54 (OP),        string=')')

8

TokenInfo(type=4  (NEWLINE),   string='')

9

TokenInfo(type=0  (ENDMARKER), string='')

(Note that for the sake of readability, I’ve omitted a few columns from the result above — metadata like starting index, ending index, a copy of the line on which a token occurs, etc.)

#code quality #code review #static analysis #static code analysis #code analysis #static analysis tools #code review tips #static code analyzer #static code analysis tool #static analyzer

Now Learn JavaScript Programming Language With Microsoft

icrosoft has released a new series of video tutorials on YouTube for novice programmers to get a hands-on renowned programming language — JavaScript.

This isn’t the first attempt by Microsoft to come up with video tutorials by beginner programmers. The company also has a series of YouTube tutorials on Python for beginners.

For JavaScript, Microsoft has launched a series of 51 videos as ‘Beginner’s Series to JavaScript,’ for young programmers, developers and coders who are interested in building browser applications using JavaScript. These video tutorials will also help programmers and coders to use relevant software development kits (SDKs) and JavaScript frameworks, such as Google’s Angular.

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“Learning a new framework or development environment is made even more difficult when you don’t know the programming language,” stated on the Microsoft Developer channel on YouTube. “Fortunately, we’re here to help! We’ve created this series of videos to focus on the core concepts of JavaScript.”

It further stated — while the tutorials don’t cover every aspect of JavaScript, it indeed will help in building a foundation from which one can continue to grow. By the end of this series, Microsoft claims that the novice programmers will be able to work through tutorials, quick starts, books, and other resources, continuing to grow on their own.

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#news #javascript #javascript tutorial #javascript tutorials #microsoft tutorials on javascript

Javascript Tutorial - Safer Coding by using JSLint

What is a linter?

Linters have been around for a long time and probably exist in one shape or form for all languages. A linter is basically a parser that parses your code and looks for mistakes. It’s a great way to save time, maintain quality and write safer code. You can plug linters in to your code editor or copy-past your code to a linting tool. Lint-ing your code is a great thing to do no matter what language you code with. You can even lint HTML, CSS and JSON. There are many different types, but here I will focus on the four most popular JavaScript linters.

Workflow comparison

Example workflow WITHOUT linter

1. Write some code
2. Save your code
3. Refresh the page and wait for the page to load
4. The inspector found an error
5. You inspect the error and it says something like… “Uncaught SyntaxError: Unexpected identifier on line 43 file…”
6. You think “that’s kind of a cryptic message”. You return to the code to see what’s actually causing the problem on line 43
7. Ah, you missed a comma between your variable declarations
8. You add the comma… var variable1 = 1, variable2 = 2;
9. Then you save the project and walk yourself through the whole process again, thinking “wow, this is a bit time consuming. I really hope I didn’t miss a comma somewhere else”

Example workflow WITH linter

1. Write code. In the meantime the linter tells you about your syntax errors.
2. You fix your mistakes
3. Save your code
4. You smile and think “wow, this is the future”

#javascript #jslint