Comments in JavaScript

Published on 7 Nov, 2020

Comments in JavaScript improve readability of the code. A comment block is not executed by JavaScript engine. In JavaScript, we can write comments using two techniques.

Single Line Comment

If the comment can be contained in one line, we can use // notation to write the comment. Here, the start of the comment is from // and the end is at the end of line.

// First line of comment
console.log("Hello"); // Comment beside the code

Multi Line Comment

When the comment text spans multiple lines, we can use /* ... */ to write the comment.

/*
Here is a comment that
takes more than one line.
*/

Multi line comment cannot be nested. Let us see what happens if we nest it.

/*
Parent comment line
/*
Child comment line
*/
*/

Above code will throw an error. Because the first */ closes the entire comment text so far. So the second */ does not have a role and is the reason for syntax error.