function createIcons(elem, data) {
        var sites = getSites(data);
        var isPrepend = data.mode == 'prepend';

        each(isPrepend ? sites.reverse() : sites, function (name) {
            var url = makeUrl(name, data);
            var link = data.initialized ? getElementsByClassName(elem, 'icon-' + name) : createElementByString('<a class="social-share-icon icon-' + name + '"></a>');

            if (!link.length) {
                return true;
            }

            link[0].href = url;

            if (name === 'wechat') {
                link[0].tabindex = -1;
            } else {
                link[0].target = '_blank';
            }

            if (!data.initialized) {
                isPrepend ? elem.insertBefore(link[0], elem.firstChild) : elem.appendChild(link[0]);
            }
        });
    }
Create site icons

@param {Element} elem
@param {Object} data