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How to use JS to implement POST across domains

php中世界最好的语言Original: 2018-05-23 13:40:331522browse

This time I will show you how to use JS to implement POST across domains. What are the precautions for implementing POST across domains with JS? . Here are practical cases, let’s take a look.

javascript Cross-domain is a very common problem, among which jsonp is the most commonly used method, but jsonp only supports get, not post, so if you want to post some data through jsonp , the head is big.

Post is implemented by generating a form in an iframe, and returns the value to the caller through postMessage.

In the first step, we first implement a back-end code that accepts jsonp. As for what language to use for implementation, you decide for yourself.

c#The code is:

protected void Page_Load(object sender, EventArgs e)
    {
      StringBuilder sbRet = new StringBuilder();
      sbRet.Append("<script>");
      sbRet.Append(Request["jsoncallback"]);
      sbRet.Append("({");
      foreach (string k in Request.Form) {
        if (k == "jsoncallback") continue;
        sbRet.Append("'"+k+"':'"+Request.Form[k]+"'");
      }
      
      sbRet.Append("});");
      sbRet.Append("</script>");
      Response.Write(sbRet.ToString());
      Response.End();
    }

For example, what you want to return to me is { userName:'user1', password:'pass1' } , when I call http://localhost/test When ?jsoncallback=callme

you actually return<script>callme({ userName:'user1', password:'pass1' })</script>.

The second step is to build a post test page in the local folder, such as d:\test.html

<form action="http://localhost/test" method="post">
　　<input type="text" name="userName" value="user1" />
　　<input type="text" name="password" value="pass1" />
  <input type="text" name="jsoncallback" value="callme" />
  <input type="submit" value="提交" />
</form>

The third step is to browse and click submit to see if the returned value is< ;script>callme({ userName:'user1', password:'pass1' }) means there is no problem with the back-end program.

The fourth step, we write a general code to implement the above html.

<!doctype html>
<html>
  <head>
   <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title>测试一哈</title>
  </head>  
  <body>   
  <script>
  //源码 开始
   function postJSONP(url, data, callback) {
    var template = '<form action="{{url}}" method="post" id="form1">';   
    for (var k in data) {
     template = template
       + ' 　<input type="text" name="&#39;+k+&#39;" value="&#39;+data[k]+&#39;" />'
    }
      template = template 
      + '　　<input type="text" name="jsoncallback" value="function callback(data) { parent.postMessage(data, \&#39;*\&#39;); } callback" />'
      + '</form>'
      + '<&#39;+&#39;script>'
      + 'document.getElementById("form1").submit();'
      + '</&#39;+&#39;script>';      
   template = template.replace("{{url}}", url);      
   var p = document.createElement("p");
   p.style.display = 'none';  
   p.innerHTML = '<iframe src=""></iframe>';
   document.body.appendChild(p);   
   var ifrm = p.children[0];
   var cwin = ifrm.contentWindow;
   cwin.document.write(template);   
   window.onmessage = function(e) {
   if (callback) callback(e.data);
   }
   }
   //源码 结束  
  //使用测试
   window.onload = function() {
   postJSONP('http://localhost:59898/WebForm1.aspx', { userName: '张静', password: '就不告诉你' }, function(data) {
    console.log(11, data);
   });
   postJSONP('http://localhost:59898/WebForm1.aspx', { 仓库: '1号大仓', 面积: '2万平米' }, function(data) {
    console.log(22, data);
   });
  }
 </script>
  </body>
</html>

The fifth step, security issues,

window.onmessage = function(e) {
  //可通过 e 来判断来源，并做一些安全方面的处理，此处读者自己去研究吧，可以加个 console.log(e) 看看 e 有哪些内容。
  if (callback) callback(e.data);
}

I believe you have read the case in this article After mastering the method, please pay attention to other related articles on the php Chinese website for more exciting content!

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