JavaScript Comments
Last Updated :
15 Nov, 2024
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Comments help explain code (they are not executed and hence do not have any logic implementation). We can also use them to temporarily disable parts of your code.
1. Single Line Comments
A single-line comment in JavaScript is denoted by two forward slashes (//),
// A single line comment
console.log("Hello Geeks!");
Output
Hello Geeks!
2. Multi-line Comments
A multiline comment begins with /* and ends with */
/* It is multi line comment.
It will not be displayed upon
execution of this code */
console.log("Multiline comment in javascript");
Output
Multiline comment in javascript
JavaScript Comments in HTML
Prerequisite : How to Add JavaScript in HTML Document?
The syntax of comments remains same when we write inside HTML script tag.
<!DOCTYPE html>
<html>
<head>
<title></title>
</head>
<body>
<script>
// Prinintg Hello World
document.write('Hello World');
</script>
</body>
</html>
JavaScript Comments to Prevent Execution
We can use // or /*...*/ to change the JavaScript code execution using comments. JavaScript Comments are used to prevent code execution and are considered suitable for testing the code.
function add() {
let x = 10;
let y = 20;
let z = x + y;
// console.log(x + y);
console.log(z);
}
add();
Output
30
Example 2: This example uses multi-line comments to prevent the execution of addition code and perform subtraction operations.
function sub() {
let x = 10;
let y = 20;
/* let z = x + y;
console.log(z); */
let z = x - y;
console.log(z);
}
sub();
Output
-10
