steady on

steady-on.js

    
function Queue() {
    this.queue = [];
}

/**
 * Add an item to the queue
 *
 * @param  {Anything} item  item to add
 * @return {Number}         queue length
 */
Queue.prototype.enqueue = function(item) {
    return this.queue.push(item);
};

/**
 * Take the first item from the queue
 *
 * @return {Anything} the item
 */
Queue.prototype.dequeue = function() {
    return this.queue.shift();
};

/**
 * Check if the queue is empty
 *
 * @return {Boolean}
 */
Queue.prototype.empty = function() {
    return this.queue.length === 0;
};

return Queue;    





// -------------------
    
    
    
    
    var q = new Queue();
    var running = false;

    function readHeight(el) {
        return fastdom.read() {
            var style = getComputedStyle(el);
            return  el.offsetHeight + parseInt(style.marginTop) + parseInt(style.marginBottom);
        };
    }

    /**
     * Process the insertion operation:
     *
     *   1. Calculate the original height of the container
     *   2. Apply the insertion function
     *   3. Calculate the new height of the container
     *   4. Adjust the scroll position to account for the new container height
     *
     * @param  {Object} insertion
     */
    function go(insertion) {
        running = true;

        readHeight(insertion.container).then(function(originalHeight) {
            return fastom.write(function() {
                insertion.cb();
            }).then(function() {
                return readHeight(insertion.container);
            }).then(function(newHeight) {
                return newHeight - originalHeight;
            });
        }).then(function(offset) {
            window.scrollTo(0, window.scrollY + offset);
        }).then(function() {
            if (q.empty) {
                running = false;
            } else {
                go(q.dequeue);
            }
        });
    }

    /*
     * Insert an element into the page
     * Use if your element doesn't exist and is inserted into a container
     * ** Don't use fastdom - it is handled in this utility **
     * @param {HTMLElement} insertionContainer The element that the component is being inserted into
     * @param {Function} insertionCallback Should contain all functionality that displays and lays-out the element
     */
    function insert(container, cb) {
        q.enqueue({
            container: container,
            cb: cb
        });

        if (!running) {
            go(q.dequeue);
        }
    }