AJAX 简介

该函数从 web 服务器请求数据并显示它：

Function loadDoc()

function loadDoc() {

var xhttp = new XMLHttpRequest();

xhttp.onreadystatechange = function() {

if (this.readyState == 4 && this.status == 200) {

document.getElementById("demo").innerHTML = this.responseText;

}

};

xhttp.open("GET", "ajax_info.txt", true);

xhttp.send();

}