getSizeElement = function (elem, dataAttr, width){
			var event;
			var parent = elem.parentNode;

			if(parent){
				width = getWidth(elem, parent, width);
				event = triggerEvent(elem, 'lazybeforesizes', {width: width, dataAttr: !!dataAttr});

				if(!event.defaultPrevented){
					width = event.detail.width;

					if(width && width !== elem._lazysizesWidth){
						sizeElement(elem, parent, event, width);
					}
				}
			}
		}
@param elem {Element}
@param dataAttr
@param [width] { number }