1591500069

Chrome DevTools: The Console

ES6 Static Number and Math Properties That We May Have Missed

ES6 introduced various math and number methods and properties. In this article, we’ll look at some useful static Number properties that we may have missed.

Number.isFinite(num)

Number.isFinite(num) is a new method that lets us check if a number is finite or not.

#programming #web-development #technology #javascript #js

1604008800

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

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.

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:

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

1591500069

Chrome DevTools: The Console

ES6 Static Number and Math Properties That We May Have Missed

ES6 introduced various math and number methods and properties. In this article, we’ll look at some useful static Number properties that we may have missed.

Number.isFinite(num)

Number.isFinite(num) is a new method that lets us check if a number is finite or not.

#programming #web-development #technology #javascript #js

1619607900

Introduction

A number is said to be the perfect number if the sum of its proper divisors (not including the number itself) is equal to the number.

To get a better idea let’s consider an example, proper divisors of 6 are 1, 2, 3. Now the sum of these divisors is equal to 6 (1+2+3=6), so 6 is said to be a perfect number. Whereas if we consider another number like 12, proper divisors of 12 are 1, 2, 3, 4, 6. Now the sum of these divisors is not equal to 12, so 12 is not a perfect number.

Programming in Python is relatively simpler and more fun when compared to other languages because of its simpler syntax, good readability. Now that we are clear with the concept of perfect number let’s write a python program to check if a number is a perfect number or not. Let’s build a python code for checking if the given user input is a perfect number or not and explore the fun in coding with python.

#data science #how to check if a number is perfect #perfect number #perfect number in python #perfect number program in python #python

1620418260

Introduction

A number is said to be the perfect number if the sum of its proper divisors (not including the number itself) is equal to the number.

To get a better idea let’s consider an example, proper divisors of 6 are 1, 2, 3. Now the sum of these divisors is equal to 6 (1+2+3=6), so 6 is said to be a perfect number. Whereas if we consider another number like 12, proper divisors of 12 are 1, 2, 3, 4, 6. Now the sum of these divisors is not equal to 12, so 12 is not a perfect number.

Programming in Python is relatively simpler and more fun when compared to other languages because of its simpler syntax, good readability. Now that we are clear with the concept of perfect number let’s write a python program to check if a number is a perfect number or not. Let’s build a python code for checking if the given user input is a perfect number or not and explore the fun in coding with python.

#data science #how to check if a number is perfect #perfect number #perfect number in python #perfect number program in python #python

1650000180

is-integer

ES2015 (ES6) `Number.isInteger`

polyfill implemented in ES3.

```
var isInteger = require("is-integer");
isInteger("hello") // -> false
isInteger(4) // -> true
isInteger(4.0) // -> true
isInteger(4.1) // -> false
```

`var isInteger = require("is-integer")`

Determines whether the provided value is an integer.

See `Number.isInteger`

.

`npm install is-integer`

Author: Parshap

Source Code: https://github.com/parshap/js-is-integer

License: View license