随笔

异步加载 js 脚本的方法有哪些？

function loadJS( url, callback=()=>{} ){
        const xhr = new XMLHttpRequest();
    xhr.open("get", url,true)
    xhr.send();
    xhr.onreadystatechange = function() {
        if (xhr.readyState == 4 && xhr.status == 200) {
            eval(xhr.responseText);
            callback()
        }
    }
}
//用法
loadJS('https://cdn.jsdelivr.net/npm/[email protected]/dist/jquery.min.js',function(){
// https页面请求http地址？相对协议、添加meta
 // [fix "insecure content was loaded over HTTPS, but requested an insecure resource" ](https://stackoverflow.com/questions/35178135/how-to-fix-insecure-content-was-loaded-over-https-but-requested-an-insecure-re)
   $($('head')[0]).append('<meta http-equiv="Content-Security-Policy" content="upgrade-insecure-requests" />')
});