<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>XMLHttpReques</title>
<script>
var xhr = ‘‘;
if (window.XMLHttpRequest) {
xhr = new window.XMLHttpRequest();
} else {
xhr = new ActiveXObject(‘Microsoft.XMLHttp‘);
}
window.onload = function () {
document.getElementById("bnt").onclick = function () {
xhr.open(‘post‘,‘后台端口路径‘,true);
xhr.setRequestHeader(‘Content-Type‘,‘application/x-www-form-urlencoded‘);
var username = document.getElementById(‘username‘).value;
var password = document.getElementById(‘password‘).value;
xhr.send( ‘memberId=‘+ username + ‘&&password=‘ + password );
xhr.onreadystatechange = function () {
// readyState:
// 0: 请求未初始化
// 1: 服务器连接已建立
// 2: 请求已接收
// 3: 请求处理中
// 4: 请求已完成，且响应已就绪
// status:
// 200: ‘ok‘
// 404: 未找到页面或接口
// xhr.responseText: 后端返回的数据
if(xhr.readyState == 4 && xhr.status == 200 ) {
document.getElementById(‘box‘).innerHTML = xhr.responseText;
var json = JSON.parse(xhr.responseText);
console.log(json);
}
}
}
}
</script>
</head>
<body>
<p>账号：<input type="text" id="username"></p>
<p>密码：<input type="password" name="" id="password"></p>
<p> <input type="button" value="登录" id="bnt"></p>
<div id="box"></div>
</body>
</html>原文：https://www.cnblogs.com/effortfordream/p/13301782.html