javascript trigger on element resize

onElementResize.js

var onElementResize = function(element, callback) {

    if (!onElementResize.watchedElementData) {

        onElementResize.watchedElementData = [];

        var checkForChanges = function() {
            onElementResize.watchedElementData.forEach(function(data) {
                if (element.offsetWidth !== data.offsetWidth ||
                    element.offsetHeight !== data.offsetHeight) {
                    data.offsetWidth = element.offsetWidth;
                    data.offsetHeight = element.offsetHeight;
                    data.callback();
                }
        });
    };

    // check for changes when window is resized
    window.addEventListener('resize', checkForChanges);

    // check when dom changes
    var observer = new MutationObserver(checkForChanges);
        observer.observe(document.body, { 
            attributes: true,
            childList: true,
            characterData: true,
            subtree: true 
        });
    }

    onElementResize.watchedElementData.push({
        element: element,
        offsetWidth: element.offsetWidth,
        offsetHeight: element.offsetHeight,
        callback: callback
    });
};