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[04] JSONP tutorial, 04jsonp tutorial

Source: Internet
Author: User
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[04] JSONP tutorial, 04jsonp tutorial
JSONP tutorial

Jsonp (JSON with Padding) is a "usage mode" of json that allows a webpage to retrieve information from another domain name (website), that is, to read data across domains.

Why do we need a special technology (JSONP) to access data from different domains (websites? This is because of the same-origin policy.

Same-origin policy, a well-known security policy proposed by Netscape, is now used by all browsers that support JavaScript.

 

 

JSONP Application 1. Server JSONP format data

If the customer wants to access: http://www.baidu.com/try/ajax/jsonp.php? Jsonp = callbackFunction.

Assume that the customer expects to return JSON data: ["mermername1", "customername2"].

The data actually returned to the client is displayed as callbackFunction (["mermername1", "customername2"]).

The jsonp. php code of the Server File is:

  1. <?php
  2. header('Content-type: application/json');
  3. // Obtain the callback function name
  4. $jsoncallback = htmlspecialchars($_REQUEST ['jsoncallback']);
  5. // Json data
  6. $json_data ='["customername1","customername2"]';
  7. // Output data in jsonp format
  8. echo $jsoncallback ."(". $json_data .")";
  9. ?>
2. The client implements the callbackFunction function.
  1. <script type="text/javascript">
  2. function onCustomerLoaded(result, methodName)
  3. {
  4. var html ='<ul>';
  5. for(var i =0; i < result.length; i++)
  6. {
  7. html +='<li>'+ result[i]+'</li>';
  8. }
  9. html +='</ul>';
  10. document.getElementById('divCustomers').innerHTML = html;
  11. }
  12. </script>
Page display 
<div id="divCustomers"></div>

　　

Complete client Page code
  1. <!DOCTYPE html >
  3. <Title> JSONP instance </title>
  5. <body>
  6. <div id="divCustomers"></div>
  7. <script type="text/javascript">
  8. function callbackFunction(result, methodName)
  9. {
  10. var html ='<ul>';
  11. for(var i =0; i < result.length; i++)
  12. {
  13. html +='<li>'+ result[i]+'</li>';
  14. }
  15. html +='</ul>';
  16. document.getElementById('divCustomers').innerHTML = html;
  17. }
  18. </script>
  19. <script type="text/javascript" src="http://www.baidu.com/try/ajax/jsonp.php?jsoncallback=callbackFunction"></script>
  20. </body>
    22.
JQuery uses JSONP

The above code can be used as an example of jQuery code:

  1. <!DOCTYPE html>
  4. <Title> JSONP instance </title>
  5. <script src="http://apps.bdimg.com/libs/jquery/1.8.3/jquery.js"></script>
  7. <body>
  8. <div id="divCustomers"></div>
  9. <script>
  10. $.getJSON("http://www.baidu.com/try/ajax/jsonp.php?jsoncallback=?", function(data){
  12. var html ='<ul>';
  13. for(var i =0; i < data.length; i++)
  14. {
  15. html +='<li>'+ data[i]+'</li>';
  16. }
  17. html +='</ul>';
  19. $('#divCustomers').html(html);
  20. });
  21. </script>
  22. </body>
    24.
 

 

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