GTM - dynamic dataLayer Name

a GTM Tag .html

<script>
  var dataLayer = window[{{dataLayer Name}}];
  dataLayer.push({ 'event' : 'test' })
</script>

GTM Variable: "dataLayer Name alternate method" .js

function(){
	var k, timestamp;
	timestamp = google_tag_manager[{{Container ID}}].dataLayer.get('gtm.start');
	for( k in window ){
		if( window[k] && window[k][0] && timestamp === window[k][0]['gtm.start'] ){
			return k;
		}
	}
}

GTM Variable: "dataLayer Name" .js

function(){
	var i, src, matches, scripts, cacheObj;
	scripts = document.getElementsByTagName( "script" );
	for( i in scripts ){
		src = scripts[i].getAttribute( 'src' );
		if( /^(?:https?:)?\/\/www\.googletagmanager\.com\/gtm\.js\?(?:.*&)?id={{Container ID}}(?:&|$)/.exec( src ) ){
			matches = /[?&]l=([^&]+)(?:&|$)/.exec( src );
			return matches ? matches[1] : 'dataLayer';
		}
	}
}