setcustomvariable.js

<script type="text/javascript">

	document.addEventListener('om.Dtr.init', function(event) {

		/**

		 * API method for setting a custom variable. Must be accessed via the Dtr object.

		 *

		 * @param string $key   The custom variable key to set.

		 * @param string $value The custom variable value to set for the key.

		 * @return null

		 */

		event.detail.Dtr.setCustomVariable('foo', 'bar');

	});

</script>