JS 换行写法

    var populatePullUpHtml = function (id) {
        var html = '<div id="' + id + '" class="' + staticOpts.pullUpClass + '" style="display: none;">
               <span class="pullUpIcon"></span><span class="pullUpLabel">上拉加载更多...</span>
            </div>';
        return html;
    }