␡
- Recipe: Setting Up an Example Server in Node.js
- Recipe: Performing a GET Request
- Recipe: Loading HTML Directly
- Recipe: Handling the Result by Using Promises
- Recipe: Handling Server Errors
- Recipe: Catching Page-not-Found Results
- Recipe: Handling Page Redirects
- Recipe: Setting Request Timeouts
- Recipe: Passing HTTP Headers
- Example: Validating Form Input on the Server Side
- Recipe: Loading XML
- Recipe: Listening to AJAX Events
- Recipe: Reading JSONP from an External Server
- Summary
This chapter is from the book
This chapter is from the book
This chapter is from the book
This chapter is from the book
Recipe: Passing HTTP Headers
If you need control over HTTP headers—for example, those used for caching—you can pass anything with the AJAX request. To test how this works, the test server from the first example returns a JSON string containing exactly the headers it received during the request.
Listing 5.9 passes a simple ETag header and displays the result returned from the test server.
Listing 5.9. Passing an ETag Header and Displaying the Returned Mirrored Headers from the Server
00 <!DOCTYPE html>
01
02 <html lang="en">
03 <head>
04 <title>The headers property</title>
05 </head>
06 <body>
07
08 <h2>Press the button to perform the request.</h2>
09
10 <button id="trigger">GET</button>
11 <br>
12 <div id="target">
13
14
15 <script src="https://code.jquery.com/jquery-1.7.2.min.js"></script>
16
17 <script>
18 // please externalize this code to an external .js file
19 $(document).ready(function() {
20
21 $('#trigger').click(function() {
22
23 $.ajax({url: 'return-http-headers',
24 headers : {
25 ETag: '12345'
26 }
27 })
28 .done(function(data, xhr) {
29 $('#target').append(
30 $.map(data.headers, function(i, name) {
31 return name + ' = '+ data.headers[name] + '<br/>';
32 })
33 .join(' ')
34 );
35 })
36 .fail(function(xhr, text, error) {
37 $('#target').append('Failed unexpectedly');
38 });
39 });
40
41 });
42 </script>
43 </body>
44 </html>
The test server returns a little bit more than just the HTTP headers, which might be useful for different tests such as ETag configuration, compression support (gzip, deflate), and even agent identification.