wp_localize_script($handle, $object_name, $l10n);
For example:
$myvars = array('value' => 'one');
wp_localize_script('my-handle', 'myVars', $myvars);

The above code won't do anything unless you enqueue a script with the same handle before it, like this:

wp_enqueue_script('my-handle', 'path-to-js-file.js');
$myvars = array('value' => 'one');
wp_localize_script('my-handle', 'myVars', $myvars);

This code will be inserted into your page:

/* <![CDATA[ */
var myVars = {
value: "one"
};
/* ]]> */

Then you can reference myVars in your script later on.