Javascript XMLHttpRequest onreadystatechanged not firing?
Javascript XMLHttpRequest onreadystatechanged not firing?
我在网络服务器上托管的同一目录中有一个html文件和一个.txt
文件。 html 文件包含以下代码:
<html>
<head>
<script>
window.onload = function() {
receiveMessage();
}
function receiveMessage() {
var xmlhttp = new XMLHttpRequest;
xmlhttp.open("GET", "message.txt", true);
xmlhttp.send();
xmlhttp.onreadystatechanged = function() {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
alert(xmlhttp.responseText);
}
}
}
</script>
</head>
<body>
</body>
</html>
由于文本文件消息.txt包含"hello world",因此在收到响应时应弹出包含该消息的javascript警报框,但事实并非如此。 我做错了什么?
您要查找的属性onreadystatechange
不是onreadystatechanged
。最后没有d
。
对
请求和更改函数重新排序 onreadystate更改为onreadystatechange:
function receiveMessage() {
var xmlhttp = new XMLHttpRequest;
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState==4 && xmlhttp.status==200) {
alert(xmlhttp.responseText);
}
}
xmlhttp.open("GET","message.txt",true);
xmlhttp.send();
}
将打开和发送呼叫放在 ONREADY 状态更改事件之后,如在 http://www.w3schools.com/ajax/ajax_xmlhttprequest_send.asp
<!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","demo_get.asp",true);
xmlhttp.send();
}
</script>
</head>
<body>
<h2>AJAX</h2>
<button type="button" onclick="loadXMLDoc()">Request data</button>
<div id="myDiv"></div>
</body>
</html>
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