method：请求的类型；GET 或 POST
open(method,url,async) url：文件在服务器上的位置
async：true（异步）或 false（同步）
send(string) 将请求发送到服务器string：仅用于 POST 请求
Get请求：<!DOCTYPE html><html><head><meta charset="utf-8"><script>function loadXMLDoc(){ ???var xmlhttp; ???if (window.XMLHttpRequest) ???{ ???????// IE7+, Firefox, Chrome, Opera, Safari 浏览器执行代码 ???????xmlhttp=new XMLHttpRequest(); ???} ???else ???{ ???????// IE6, IE5 浏览器执行代码 ???????xmlhttp=new ActiveXObject("Microsoft.XMLHTTP"); ???} ???xmlhttp.onreadystatechange=function() ???{ ???????if (xmlhttp.readyState==4 && xmlhttp.status==200) ???????{ ???????????document.getElementById("myDiv").innerHTML=xmlhttp.responseText; ???????} ???} ???xmlhttp.open("GET","/try/ajax/demo_get.php",true); ???xmlhttp.send();}</script></head><body><h2>AJAX</h2><button type="button" onclick="loadXMLDoc()">请求数据</button><div id="myDiv"></div></body></html>POST:<!DOCTYPE html><html><head><meta charset="utf-8"><script>function loadXMLDoc(){ ?var xmlhttp; ?if (window.XMLHttpRequest) ?{ ???// IE7+, Firefox, Chrome, Opera, Safari 浏览器执行代码 ???xmlhttp=new XMLHttpRequest(); ?} ?else ?{ ???// IE6, IE5 浏览器执行代码 ???xmlhttp=new ActiveXObject("Microsoft.XMLHTTP"); ?} ?xmlhttp.onreadystatechange=function() ?{ ???if (xmlhttp.readyState==4 && xmlhttp.status==200) ???{ ?????document.getElementById("myDiv").innerHTML=xmlhttp.responseText; ???} ?} ?xmlhttp.open("POST","/try/ajax/demo_post2.php",true); ?xmlhttp.setRequestHeader("Content-type","application/x-www-form-urlencoded"); ?xmlhttp.send("fname=Henry&lname=Ford");}</script></head><body><h2>AJAX</h2><button type="button" onclick="loadXMLDoc()">请求数据</button><div id="myDiv"></div> </body></html>
ajax请求
原文地址：https://www.cnblogs.com/CY-947205926/p/8906051.html