1、 添加脚本加载的状态事件。

 _scriptOnload = doc.createElement(‘script‘).readyState ?
            function(node, callback) {
                var oldCallback = node.onreadystatechange;
                node.onreadystatechange = function() {
                    var rs = node.readyState;
                    if (rs === ‘loaded‘ || rs === ‘complete‘) {
                        node.onreadystatechange = null;
                        oldCallback && oldCallback();
                        callback.call(this);
                    }
                };
            } :
            function(node, callback) {
                node.addEventListener(‘load‘, callback, false);
            };

2、 为界面添加 加载脚本的Js, 

    head = doc.getElementsByTagName(‘head‘)[0] || doc.documentElement,
        _getScript = function(url, fn) {
            var node = doc.createElement(‘script‘);
            node.src = url;
            node.async = true;
            _scriptOnload(node, function() {
                fn && fn.call(node, ‘‘);
                if (head && node.parentNode) {
                    head.removeChild(node);
                }
            });
            head.insertBefore(node, head.firstChild);
            return node;
        }