hascustomvariable.js

<script type="text/javascript">

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

		/**

		 * API method for checking if a custom variable has been registered.

		 * Must be accessed via the Dtr object.

		 *

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

		 * @return bool       True if the custom variable exists, false otherwise.

		 */

		event.detail.Dtr.hasCustomVariable('foo');

	});

</script>