JavaScript: The Definitive Guide, 6th Edition

Comments

JavaScript supports two styles of comments. Any text between a // and the end of a line is treated as a comment and is ignored by JavaScript. Any text between the characters /* and */ is also treated as a comment; these comments may span multiple lines but may not be nested. The following lines of code are all legal JavaScript comments:

// This is a single-line comment.
/* This is also a comment */  // and here is another comment.
/*
 * This is yet another comment.
 * It has multiple lines.
 */