Display images from firebase storage in html img tags

I'm attempting to display an image from firebase into html img tags, but it fails to retrieve the image.

Javascript code:

    var storageRef = firebase.storage().ref();
    var spaceRef = storageRef.child('images/photo_1.png');
    var path = spaceRef.fullPath;
    var gsReference = storage.refFromURL('gs://test.appspot.com')

    storageRef.child('images/photo_1.png').getDownloadURL().then(function(url) {


     var test = url;

    }).catch(function(error) {

    });

html code:

    <img src="test" height="125" width="50"/>