vue動態加載js文件，加載完成后執行回調

方法定義：

loadScript(src, callback) {
    var script = document.createElement('script'),
        head = document.getElementsByTagName('head')[0];
    script.type = 'text/javascript';
    script.charset = 'UTF-8';
    script.src = src;
    if (script.addEventListener) {
        script.addEventListener('load', function () {
            callback();
        }, false);
    } else if (script.attachEvent) {
        script.attachEvent('onreadystatechange', function () {
            var target = window.event.srcElement;
            if (target.readyState == 'loaded') {
                callback();
            }
        });
    }
    head.appendChild(script);
}

調用：

var that=this;//監聽函數中的this不再指向組件本身，而是指向事件監聽者,所以需要提前保存this指針
this.loadScript('xxx.js',function(){
    console.log('加載完成');
});