一、处理数据：
将一些数据发送到服务器并接收响应 【post请求】
<label>Your name: <input type="text" id="ajaxTextbox" /> </label> <span id="ajaxButton" style="cursor: pointer; text-decoration: underline"> Make a request </span> //1、步骤 document.getElementById("ajaxButton").onclick = function() { var userName = document.getElementById("ajaxTextbox").value; // makeRequest('test.php',userName); }; //2、发送请求 function makeRequest(url, userName) { ... httpRequest.onreadystatechange = alertContents; //POST请求， httpRequest.open('POST', url); // httpRequest.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded'); //将数据作为参数 包含在对的调用中http...send() httpRequest.send('userName=' + encodeURIComponent(userName)); } //3、响应处理 function alertContents() { if (httpRequest.readyState === XMLHttpRequest.DONE) { if (httpRequest.status === 200) { // var response = JSON.parse(httpRequest.responseText); alert(response.computedString); } else { alert('There was a problem with the request.'); } } }
二、定时XHR例子：
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>XHR log time</title>
<style>
</style>
</head>
<body>
<p id="writeData" class="data">Off-Line</p>
<p id="lastStamp">No Data yet</p>
<script>
const fullData = document.getElementById('writeData');
const lastData = document.getElementById('lastStamp');
function fetchData() {
console.log('Fetching updated data.');
//1、发出请求
let xhr = new XMLHttpRequest();
// 2、发出实际请求
xhr.open("GET", "time-log.txt", true);
// 3、
xhr.onload = function() {
//
updateDisplay(xhr.response);
}
xhr.send();
}
function updateDisplay(text) {
//
fullData.textContent = text;
//
let timeArray = text.split('
');
//
if(timeArray[timeArray.length-1] === '') {
//
timeArray.pop();
}
//
lastData.textContent = timeArray[timeArray.length-1];
}
//电话每5秒重复一次
setInterval(fetchData, 5000);
</script>
</body>
</html>