recents.js

    // Load n more call records into a list
    loadN(list, n) {
        var pages = this.get('pages');
        // This serves two purposes, allowing us to access the contents of the pages,
        // but also preventing us from making concurrent requests and screwing up the
        // ordering
        return Ember.RSVP.all(pages).then(pagesData => {
            // We want to be adding items from the start if we currently have no items
            var addingItems = list.length == 0;
            // Loop through pages while there are still pages to go through, and we
            // haven't yet added the full n items. Add items to our list.
            for (var pageNo=0; pageNo<pagesData.length && n; pageNo++) {
                // The oldest item is the last in the list.
                var oldest = list.slice(-1)[0];
                var page = pagesData[pageNo];
                // If posInPage is not -1 then we have found the oldest item in the
                // list. In that case we should start adding items after. If it is -1
                // and we are adding, then we should start adding items from position
                // 0. In both of these cases we will start from posInPage + 1.
                var posInPage = page.indexOf(oldest);
                if (addingItems = addingItems || posInPage != -1) { // Assignment is intended
                    // We want to all the remaining items in the list, or n, whatever is smaller
                    var addingNo = Math.min(page.length - posInPage - 1, n);
                    list.pushObjects(page.slice(posInPage + 1, posInPage + addingNo + 1));
                    // We now don't need as many items
                    n -= addingNo;
                }
            }
            // If we don't have enough records in our stored pages, then request
            // another page
            if (n) {
                var proxy = this._request(n);
                pages.pushObject(proxy);
                // Do not resolve our current promise until the new page has loaded
                // and we've added the contents
                return proxy.then(data => {
                    list.pushObjects(data);
                });
            }
        });
    }