在 Javascript 请求后使用 Javascript 从服务器获取响应
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Get response from server with Javascript after Javascript request
提问by Murat
My Javascript function request to a aspx page. ?ts Code:
我对 aspx 页面的 Javascript 函数请求。?ts 代码：
var xhr = ("XMLHttpRequest" in window) ? new XMLHttpRequest() : new ActiveXObject("Msxml3.XMLHTTP");
xhr.open("GET", = 'http://www.example.net/abc.aspx', true);
xhr.send("");
After this request I want to send a response back from this page and catch it on the client side. How do I do that?
在此请求之后，我想从此页面发回响应并在客户端捕获它。我怎么做？
回答by Daniel Vassallo
To get the response from XMLHttpRequestin asynchronous mode (third parameter is truefor the open()method) you have to set the onreadystatechangeproperty to a callback function. This function will be called back when the response is ready at the browser:
要XMLHttpRequest以异步模式（第三个参数true用于open()方法）获取响应，您必须将该onreadystatechange属性设置为回调函数。当浏览器准备好响应时，将回调此函数：
xhr.open("GET", 'http://www.example.net/abc.aspx', true);
xhr.onreadystatechange = function() {
if (xhr.readyState === 4) {
var serverResponse = xhr.responseText;
}
};
xhr.send(null);
You may want to check out the following article for further reading on the topic:
您可能需要查看以下文章以进一步阅读该主题：
回答by bobince
To get the response, add a readystatechangeevent handler function. This will get called back when the response is ready to read:
要获得响应，请添加readystatechange事件处理函数。当响应准备好读取时，这将被回调：
xhr.onreadystatechange= function() {
if (this.readyState!==4) return; // not ready yet
if (this.status===200) { // HTTP 200 OK
alert(this.responseText);
} else {
// server returned an error. Do something with it or ignore it
}
};
xhr.open('GET', 'http://www.example.net/abc.aspx', true);
xhr.send();
Incidentally:
顺便：
("XMLHttpRequest" in window)
Whilst inis in general a good way to test whether a property exists, this is one of the very few places where it's not ideal.
虽然in通常是测试属性是否存在的好方法，但这是极少数不理想的地方之一。
The problem is that in IE7+, when the ‘native XMLHttpRequest' option is turned off, XMLHttpRequeststill exists as a property in window, but with the unusable value null. So it's better in this specific case to use a simple truth test, which will allow fallback to ActiveX in the (unlikely) event that this option is disabled:
问题在于，在 IE7+ 中，当“native XMLHttpRequest”选项关闭时，XMLHttpRequest仍然作为 中的属性存在window，但值不可用null。因此，在这种特定情况下最好使用简单的真值测试，这将允许在禁用此选项的（不太可能）事件中回退到 ActiveX：
var xhr= window.XMLHttpRequest? new XMLHttpRequest() : new ActiveXObject('MSXML2.XMLHttp');
回答by gblazex
You have to do a little moreto get it work cross-browser, but once it's done you've got a reusable function, without any library.
您必须做更多的工作才能使其跨浏览器工作，但是一旦完成，您就拥有了一个可重用的函数，而无需任何库。
// making a call is as simple as this
ajax( "http://www.example.net/abc.aspx", function( data ){
// do something with the server's response
alert(data);
});
///////////////////////////////////////////////////////////////////////////////
function getXmlHttpObject() {
var xmlHttp;
try {
// Firefox, Opera 8.0+, Safari
xmlHttp = new XMLHttpRequest();
} catch (e) {
// Internet Explorer
try {
xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e) {
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
}
}
if (!xmlHttp) {
alert("Your browser does not support AJAX!");
}
return xmlHttp;
}
function ajax(url, onSuccess, onError) {
var xmlHttp = getXmlHttpObject();
xmlHttp.onreadystatechange = function() {
if (this.readyState === 4) {
// onSuccess
if (this.status === 200 && typeof onSuccess == 'function') {
onSuccess(this.responseText);
}
// onError
else if(typeof onError == 'function') {
onError();
}
}
};
xmlHttp.open("GET", url, true);
xmlHttp.send(null);
return xmlHttp;
}?
