Newest version of javascript

As the Codex tells us you can add another parameter to the function that holds the version number.

wp_register_script( $handle, $src, $deps, $ver, $in_footer );

$ver
String specifying the script version number, if it has one, which is concatenated to the end of the path as a query string. If no version is specified or set to false, then WordPress automatically adds a version number equal to the current version of WordPress you are running. If set to null no version is added. This parameter is used to ensure that the correct version is sent to the client regardless of caching, and so should be included if a version number is available and makes sense for the script.

So if you add a string, like 1.2.3 as fourth parameter, this is added to the end of your registered javascript file.