displayImage.js

// Display Thread/Comment Image
const displayImage = (folder, id, element, background) => {
  const ref = firebase.storage().ref(folder);
  const name = id + '.jpg';

  ref.child(name)
    .getDownloadURL()
    .then(url => {
      (background)
        ? document.getElementById(element).style.backgroundImage = 'url(' + url + ')'
        : document.getElementById(element).src = url;
    }).catch();
}