JavaScript Coding Style and Comments (Best Practice)

As a programmer /developer, our code must be as clean and easy to read. We need to write comments to understand the codes for others.

Coding Style

function pow(num, sup) {
  let result = 1;
  for (let i = 0; i < sup; i++){
    result *= number;
  }
  
  return result;
}
let num= prompt("x?", "");
let sup= prompt("n?", "");
if(num < 0) {
  alert(`${num} is not valid,
    please enter a non-negative integer number`);
} else {
  alert( pow(num, sup) );
}

Curly Braces

Bad practice of writing JavaScript code:-

if (n < 0) {alert(‘${num} is not valid’);}
or,
if (n < 0)
  alert(‘${num} is not valid’)
or,
if (n < 0) alert(‘${num} is not valid’);

Best practice to use Curly Braces:-

if (n < 0) {
  alert(‘${num} is not valid’); // 2 space indentation
}

Line Length

Long Horizontal code is bad. It’s very irritating for code readers.

const str = “JavaScript is a lightweight, interpreted, or just-in-

in if statement:

if ( num !== condition1 && sup ≥ 0 && num ≥ 1 ) { 
  return pow(num, sup); 
}

You need to split the long code.

const str = `JavaScript is a lightweight, interpreted, or 
             just-in-time compiled programming language 
             with first-class function`;

for if statement:

if (
  number !== condition1 &&
  super ≥ 0 &&
  number ≥ 1
) { 
  return pow(num, sup); 
}

Code Indentation

There are two types of Code Indentation.
1. Horizontal Code Indentation
2. Vertical Code Indentation
Horizontal Indents: 2 or, 4 spaces for horizontal indentation is best practice for writing code.

for (let i = 0; i < sup; i++){
  result *= number; // 2 spaces
}
or,
for (let i = 0; i < sup; i++){
    result *= number; // 4 spaces
}

Vertical Indents: Splitting the code into logical blocks using empty lines
function pow(num, sup) {
let result = 1;

for (let i = 0; i < sup; i++){
 result *= number;
 }
 
 return result;
}

Semicolons

You must need to use a semicolon after each code statement.

let num = prompt(“x?”, “”);
let sup = prompt(“n?”, “”);

Nested Code

Always Try to avoid Nesting code too many levels deep.
You can use the continue or, return keyword to avoid nested code.

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use of continue keyword

for(let i = 0; i < n; i++) {
  if(i % 2 === 0) {
    // code
  }
}

Avoid nesting with continue keyword:-

for(let i = 0; i < 10; i++) {
  if(i % 2 === 0) continue;
  // code
}

use of return keyword

function pow(num, sup) {
  if (num < 0) {
    console.log('Please Enter Positive Number!');
  } else {
    let result = 1;
    for (let i = 0; i < sup; i++){
      result *= num;
    }
    
    return result;
  }
}

avoid nesting using the return keyword

function pow(num, sup) {
  if (num < 0) {
    console.log('Please Enter Positive Number!');
    return;
  }
  
  let result = 1;
  for (let i = 0; i < sup; i++){
    result *= num;
  }
    
  return result;
}