load youtube js

app.js

function onYouTubeIframeAPIReady() {
    console.log( 'youtube api loaded' );
    $( document ).trigger('youtube-ready');
}
requirejs( [
        'jquery' ,
    ] ,
    function ( $ ) {

        /**
         * try to use this https://github.com/millermedeiros/requirejs-plugins/pull/39
         * but failed
         */
        function getYT() {
            console.log('started');
            var tag = document.createElement( 'script' );
            tag.src = "https://www.youtube.com/iframe_api";
            var firstScriptTag = document.getElementsByTagName( 'script' )[ 0 ];
            firstScriptTag.parentNode.insertBefore( tag , firstScriptTag );
        }

        $(function(){
            getYT();
        });
    }
);