XHR create object
XMLHttpRequest is the foundation of AJAX.
XMLHttpRequest Object
The XMLHttpRequest object is supported by all modern browsers (IE5 and IE6 use ActiveXObject).
XMLHttpRequest is used to exchange data with the server in the background. This means that parts of a web page can be updated without reloading the entire page.
Create XMLHttpRequest object
All modern browsers (IE7+, Firefox, Chrome, Safari and Opera) have built-in XMLHttpRequest objects.
Syntax for creating an XMLHttpRequest object:
Old version of Internet Explorer (IE5 and IE6) use ActiveX objects:
To cope with all modern browsers , including IE5 and IE6, please check whether the browser supports the XMLHttpRequest object. If supported, creates an XMLHttpRequest object. If it is not supported, create an ActiveXObject::
Instance
<html><!DOCTYPE html>
<html>
<head>
<script>
function loadXMLDoc()
{
var xmlhttp;
if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
else
{// code for IE6, IE5
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/ajax_info.txt",true);
xmlhttp.send();
}
</script>
</head>
<body>
<div id="myDiv"><h2>使用 AJAX 修改该文本内容</h2></div>
<button type="button" onclick="loadXMLDoc()">修改内容</button>
</body>
</html>Run Instance»
Click the "Run Instance" button View online examples
In the next chapter, you will learn about sending server requests.
