I use JDzoom (https://donatstudios.com/JDZoom) but I have error

on-line: var elmSize = $(elm).getSize();
var JDZoom = new Class({
Implements: [Options],
Images: [],
options: {
    'selector': 'a[rel=jdzoom]',
    'classes': {
        placeholder  : 'jdz_img',
        looking_glass:'jdz_looking_glass',
        magnified: 'jdz_magnified'
    },
    'cancel_click' : true,
    'magnified_pos': 'float'
},
initialize:  function(options) { 
    this.setOptions(options);       
    this.Images = $$( this.options.selector + ' img' );
    var that = this;
    this.Images.each(function(elm, i){
        var elmSize = $(elm).getSize();
        var parent_a = elm.getParent('a');
        var lg_href = parent_a.get('href');
        parent_a.setStyles({'position':'relative','display':'block'});
        var rel_pos = parent_a.getPosition( elm );
        if( that.options.cancel_click ) {
            parent_a.addEvent('click', function(e){
                e.preventDefault();
            });
        }
I read: 1 getSize() giving me errors 2 https://github.com/magento/magento2/issues/7730 3 How to get the size of a JavaScript object?
But not find answer. Anyone have idea?
 
    