JS——我的第一个AJAX程序

common.js

//common.js
function $(id){
	return document.getElementById(id);
}
var xhr;
function createXhr() {
	if(window.XMLHttpRequest){
		xhr = new XMLHttpRequest();
		return xhr;
	}else{
		xhr = new ActiveXObject("Microsoft XMLHttp");// Microsoft XMLHttp大小写随意
		return xhr;
	}
}

index.html

<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
	<script src="common.js"></script>
</head>
<body>
	<button onclick="getMsg()">发送请求</button>
	<div id="show"></div>
	<script>
		function getMsg(){
			//1. 创建xhr
			var xhr = createXhr();
			console.log(xhr);
			//2. 创建请求
			xhr.open("GET","04-response.php",true);
  		 	//3. 设置回调函数—onreadystatechange
  		 	xhr.onreadystatechange = function() {
  		 		if(xhr.readyState == 4 && xhr.status == 200){ //status
  		 			//接收响应数据
  		 			console.log("1111");
  		 			var resText = xhr.responseText;
  		 			$("show").innerHTML = resText;
  		 			console.log(resText);
  		 		}
  		 	}
  		 	//4. 发送请求
  		 	xhr.send();
		}
	</script>
</body>
</html>

04-response.php

<?php 
	
	echo "我的第一个AJAX程序";
?>