动态引入js文件，并让其执行

【动态创建script来加载-推荐】

function loadJS( url, callback ){

var script = document.createElement('script'),

    fn = callback || function(){};

script.type = 'text/javascript';



//IE

if(script.readyState){

    script.onreadystatechange = function(){

        if( script.readyState == 'loaded' || script.readyState == 'complete' ){

            script.onreadystatechange = null;

            fn();

        }

    };

}else{

    //其他浏览器

    script.onload = function(){

        fn();

    };

}

script.src = url;

document.getElementsByTagName('head')[0].appendChild(script);

}

//用法

loadJS('file.js',function(){

alert(1);

});

引用：https://www.cnblogs.com/telwanggs/p/11045773.html