function ImagesLoaded( elem, options, onAlways ) {
  // coerce ImagesLoaded() without new, to be new ImagesLoaded()
  if ( !( this instanceof ImagesLoaded ) ) {
    return new ImagesLoaded( elem, options, onAlways );
  }
  // use elem as selector string
  var queryElem = elem;
  if ( typeof elem == 'string' ) {
    queryElem = document.querySelectorAll( elem );
  }
  // bail if bad element
  if ( !queryElem ) {
    console.error( 'Bad element for imagesLoaded ' + ( queryElem || elem ) );
    return;
  }

  this.elements = makeArray( queryElem );
  this.options = extend( {}, this.options );
  // shift arguments if no options set
  if ( typeof options == 'function' ) {
    onAlways = options;
  } else {
    extend( this.options, options );
  }

  if ( onAlways ) {
    this.on( 'always', onAlways );
  }

  this.getImages();

  if ( $ ) {
    // add jQuery Deferred object
    this.jqDeferred = new $.Deferred();
  }

  // HACK check async to allow time to bind listeners
  setTimeout( this.check.bind( this ) );
}
@param {Array, Element, NodeList, String} elem
@param {Object or Function} options - if function, use as callback
@param {Function} onAlways - callback function