JavaScript Tutorial
11. Commenting
Comments allow you to write notes to yourself within your program. These are important because they allow someone to browse your code and understand what the various functions do or what your variables represent. Comments also allow you to understand your code if it's been a while since you last looked at it.
In JavaScript, you can write both one-line comments and multiple line comments. The notation for each is different though. For a one line comment, you precede your comment with //. This indicates that everything written on that line, after the //, is a comment and the program should disregard it.
For a multiple-line comment, you start with /* and end with */ . It is nice to put an * at the beginning of each line just so someone perusing your code realizes that he/she is looking at a comment (if it is really long this helps). This is not necessary though.
The following are examples of comments in JavaScript.