Different Ways To Write Comments in JavaScript

Everything you need to know before you code

Fatima Nawaz
Nov 30, 2020 · 5 min read
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Photo by Goran Ivos on Unsplash


Comment Syntax

// This is a comment
/* This is
a comment */
// Print "Hello, World!" to the console
console.log("Hello, World!");
// Initialize a function
function alphabetizeOceans() {
// Define oceans variable as a list of strings
const oceans = ["Pacific", "Atlantic", "Indian", "Antarctic", "Arctic"];
// Print alphabetized array to the console

Inline Comments

let x = 99;    // assign numerical value to x
let y = x + 2; // assign the sum of x + 2 to y
for (let i = 0; i === 10; i++) // for loop that runs ten times {
// Running this code results in a syntax error

Block Comments

/* Initialize and invoke a the greetUser function
to assign user's name to a constant and print out
a greeting. */
function greetUser() {
const name = prompt("What is your name?");
console.log("Hello ," + name + "! How are you?");
* Initialize constant with an array of strings.
* Loop through each item in the array and print
* it to the console.
const seaCreatures = ["Shark", "Fish", "Octopus"];for (const seaCreature of seaCreatures) {

Commenting Out Code for Testing

// Function to add two numbers
function addTwoNumbers(x, y) {
let sum = x + y;
return sum;
// Function to multiply two numbers
function multiplyTwoNumbers(x, y) {
let product = x * y;
return product;
/* In this example, we're commenting out the addTwoNumbers
function, therefore preventing it from executing. Only the
multiplyTwoNumbers function will run */
// addTwoNumbers(3, 5);
multiplyTwoNumbers(5, 9);


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