cacheImagesThenCallback

Cache Images Then Callback

    /**
     * Pass an Array of image urls and it will run `callback` once they are cached.
     *
     * @example
        cacheImagesThenCallback([image.jpg, picture.png], function() {
            ...
        });
     * @alias CORE.cacheImagesThenCallback
     * @constructor
     * @param imageSrcArray {array} Array of image urls.
     * @param callback {function} Callback function
     */
    var cacheImagesThenCallback = function (imageSrcArray, callback) {
        /**
         * @type {number} Load Status
         */
        var loadStatus = 1;

        /**
         * Checks to see if all images have been loaded.
         */
        function checkLoadStatus () {
            loadStatus === imageSrcArray.length ? callback() : loadStatus++;
        }

        /**
         * We go through every url and load it in memory.
         * We then check the status of the the entire array of images on load.
         */
        imageSrcArray.forEach(function(item){
            var img = new Image();
            img.src = item;
            img.onload = checkLoadStatus;
        });
    };