JavaScript » Statements » Comment

Syntax:
// comment text
/* multiple line comment text */

Examples

Code:
// This is a single-line comment.
Explanation:

Comments are notes by the author explaining what the script does, and are ignored by the interpreter. A comment consisting of a single line is preceded by a double slash (//).

Code:
/* This is a multiple line comment. It can contain whatever letters and characters you like and span as many lines as you like. */
Explanation:

...and a multiple line comment is preceded by a /* and followed by a */.