function setUrl(){
    var realUrl =document.getElementById('url').href;
    var ajax = new XMLHttpRequest();
    ajax.open('post','https://t.iamwaiting.cn/url/intoShortUrl');
    ajax.setRequestHeader("content-type","application/x-www-form-urlencoded");
    ajax.send(`realUrl=${realUrl}`);
    ajax.onreadystatechange = function () {
        if(ajax.readyState==4&&ajax.status==200){
            let obj = JSON.parse(ajax.responseText)
            let res = obj.data.shortUrl
            document.getElementById("url").href=res;
            document.getElementById("url").innerHTML=res;
        }  
    }
}