Comments in Javascript

Javascript supports two types of comments. Double-slashes (//) tell javascript to ignore everything to the end of the line. You will see them used most often to describe what is happening on a particular line.

[code type="JavaScript"]
var x=5; // Everything from the // to end of line is ignored(*)
var thingamajig=123.45; // 2 times the price of a whatsit.
[/code]

Block quotes begin a comment block with a slash-asterisk (/*) and Javascript will ignore everything from the start of the comment block until it encounters an asterisk-slash (*/). Block quotes are useful for temporally disabling large areas of code, or describing the purpose of a function, or detailing the purpose and providing credits for the script itself.

[code type="JavaScript"]
function whirlymajig(jabberwocky) {
/* Here we take the jabberwocky and insert it in the gire-gimble,
taking great care to observe the ipsum lorum! For bor-rath-outgrabe!
We really should patent this! */
return (jabberwocky*2);
}

[/code]

You should note that while comments are useful for maintaining the code, they are a liability itself in Javascript since they will be transmitted along with the code to each and every page load, which can create substantial bandwidth penalties and increase the load time of your page for users.