js判断异步js加载完毕

let j = d.createElement('script');

j.async = true;

j.src ='js地址';

if (typeof callback === "function") {

if (typeof document.attachEvent !== "object") {

j.onload = function () {

callback(); // 回调函数调用

};

} else {

j.onreadystatechange = function () {

var r = j.readyState;

if (r === "loaded" || r === "complete") {

j.onreadystatechange = null;

callback(); // 回调函数调用

}

};

}

}

d.body.appendChild(j);