Comments in Javascript

How to use comments in the Javascript. There are two methods for using commments in the javascript that are
(1) // double slash for single line comment.

(2) /* comments writes here */ for multiple line comments.
Example is shown below:-

<script> //this comment is used for single line... /* This comment is used for multiple line.*/ </script>

Comments does not shows in the display. Thats why the display is blank.