Decrypt jsonp cross-domain request in detail_javascript skills
1. What is a cross-domain request:
A page on server A needs to request a handler on server B. This is called a cross-domain request
The test page this time is:
The handler kimhandler.ashx is as follows:
%@ WebHandler Language="C#" Class="KimHandler" %>
using System;
using System.Web;
public class KimHandler : IHttpHandler {
public void ProcessRequest (HttpContext context)
{
string msg = "{\"name\":\"kim\",\"gender\":\"男\",\"age\":24}";
context.Response.Write(msg);
}
public bool IsReusable {
get {
return false;
}
}
}
Another handler.ashx is as follows:
<%@ WebHandler Language="C#" Class="Handler" %>
using System;
using System.Web;
public class Handler : IHttpHandler {
public void ProcessRequest (HttpContext context)
{
string callbackName = context.Request.Params["callbackFun"];
string msg = callbackName+ "({\"name\":\"kim\",\"age\":\"18\"});";
context.Response.Write(msg);
}
public bool IsReusable {
get {
return false;
}
}
}
2.Ajax cannot implement cross-domain requests
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title></title>
<script>
var requestUrl = "http://qxw1192430265.my3w.com/kimhandler.ashx";
window.onload = function () {
document.getElementById("btnAjax").onclick = function() {
var xhr = new XMLHttpRequest();
xhr.open("get", requestUrl, true);
xhr.setRequestHeader("If-Modified-Since", 0);
xhr.onreadystatechange = function () {
if (xhr.readyState == 4 && xhr.status == 200) {
var res = xhr.responseText;
alert(res);
}
}
xhr.send(null);
}
}
</script>
</head>
<body>
<input type="button" id="btnAjax" value="点击" />
</body>
</html>
Check the monitor and find that no request message body was returned
3. Use script tags to implement cross-domain requests
The test code is as follows:
<!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <title></title> <script src="http://qxw1192430265.my3w.com/kimhandler.ashx"></script> </head> <body> </body> </html>
Looking at the monitor, you can see that there is a request message body returned
Look at it in json format
4. Use js method , and on the browser side, read the response as data
The test code is as follows, please note that a handler has been changed
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title></title>
<script>
function getData(data) {
for (var key in data) {
alert(data[key]);
}
}
</script>
<script src="http://qxw1192430265.my3w.com/handler.ashx?callbackFun=getData"></script>
</head>
<body>
</body>
</html>Through the background code, you can know
Then look at it on the monitor
I found that on the browser side, kim and 18 popped up
5. Use Jq to implement cross-domain requests (the internal principle is to create a script tag for us)
The code is as follows
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title></title>
<script src="jquery-1.9.0.js"></script>
<script>
var requestUrl = "http://qxw1192430265.my3w.com/handler.ashx";
window.onload = function () {
document.getElementById("btnJq").onclick = function() {
$.ajax(requestUrl, {
type: "get", //请求方式
dataType: "jsonp", //数据发送类型
jsonp: "callbackFun", //服务器端接收的参数
jsonpCallback: "fun", //js处理方法
success: function () {
alert("成功");
}
});
}
}
function fun(data) {
for (var key in data) {
alert(data[key]);
}
}
</script>
</head>
<body>
<input type="button" id="btnJq" value="Jq按钮" />
</body>
</html>
After clicking the button, you can see the effect, and then look at the monitor
The above is the entire content of this article, I hope you all like it.
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