js 动态加载js 并执行

    function loadJS(url, success) {
            var domScript = document.createElement('script');
            domScript.src = url;
            success = success || function () {};
            domScript.onload = domScript.onreadystatechange = function () {
                if (!this.readyState || 'loaded' === this.readyState || 'complete' === this.readyState) {
                    success();
                    this.onload = this.onreadystatechange = null;
                    this.parentNode.removeChild(this);
                }
            }
            document.getElementsByTagName('head')[0].appendChild(domScript);
        }
        loadJS("1.js");
    </script>

转自  http://yijiebuyi.com/blog/2b23b571a0d5c94047f7e9c3150ac25d.html

!function loadJS(){
    var jsFile = [
        {name:'file1',path:'js/file1.js',active:false,load:false},
        {name:'file2',path:'js/file2.js',active:false,load:false},
        {name:'file3',path:'js/file3.js',active:false,load:false},
        {name:'file4',path:'js/file4.js',active:false,load:false},
        {name:'file5',path:'js/file5.js',active:false,load:false}
    ]
    jsFile.forEach(function(item, index){
        if(localStorage['file_' + item.name]){
            item.load = true
            implementJS(item, index)
        }else{
            $.ajax({
                type:"get",
                url:item.path,
                dataType:'text',
                success:function(data){
                    item.content = data
                    item.load = true
                    implementJS(item, index)
                }
            });
        }
    })

    function implementJS(item, index){
        //如果上一个文件已经执行了，则执行这个js文件
        if(index == 0 || jsFile[index - 1].active){
            storageJS(item, index)
            //尝试执行下一个js文件
            jsFile[index + 1] && jsFile[index + 1].load && implementJS(jsFile[index + 1], index + 1)
        }
    }
    function storageJS(item, index){
            //存储并执行js文件
            var name = 'file_' + item.name
            localStorage[name] = item.content || localStorage[name] || ''
            //这里要使用window.eval或者eval.call(window),否则eval里面的变量就不是全局变量
            window.eval(localStorage[name])
            item.active = true
    }
}()

//转自  https://segmentfault.com/a/1190000017548171