Head Rush Ajax

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Chapter 5

OK, I get it. In a GET request, the data is part of the

request URL, so it has to be just text. But in a POST

request, you can send an image, or XML, or plain text...

so we just need to tell the server what to expect.

You can send a lot more than plain text in a POST

request... as you’ll nd out in the next chapter.

But when a server receives your POST request, it

doesn’t know what kind of data it’s dealing with,

unless you tell the server what to expect.

Once the server knows what kind of data you’re

sending, it can decode the POST data, and handle

it properly. In the Break Neck app, that means

passing on the text for the address and order to

placeOrder.php... and making sure customers

are getting their pizza once again.

You need to set the content type

Servers get information from the

browser using request headers.

Web Browser

Internet Explorer

Firefox

Opera

Safari

Mozilla

<script>

var request...

function foo()

{

...

}

</script>

request.setRequestHeader(

“Content-Type”, “application/x-www-form-urlencoded”)

request headers

Hypertext Transfer Protocol

POST /placeOrder.php HTTP/1.1

Request Method: POST

Request URI: /placeOrder.php

Request Version: HTTP/1.1

Host: www.headrstlabs.com

Keep-Alive: 300

Connection: keep-alive

Content-Type:

application/x-www-form-urlencoded

Content-Length: 121

Here’s the request your

JavaScript sends to the server.

This is the request header

you added to the ...