ajax

var xhr=window.XMLHttpRequest?new XMLHttpRequest():new ActiveXObject("Microsoft.XMLHTTP");
xhr.onreadystatechange=function () {
    if(xhr.readyState==4&&xhr.status==200){
        console.log(this.responseText);
    }else{
        console.log("失败");
        console.log(xhr.getAllResponseHeaders());
    }
}
xhr.open("get","1.txt");
xhr.send();