Head Rush Ajax

you’re on your way 4

301

post requests

But isn’t the URL always the same in

a POST request? Why doesn’t the

browser try and use its cache, if the

URL never changes?

In a POST request, the browser doesn’t

know what data might be a part of the

request, since the data isn’t sent as part

of the request URL. Since the browser

isn’t sure what’s in the request, it sends

all POST requests on to their destination

server, and doesn’t try and cache

responses from the server.

Browsers hate a mystery

Web Browser

Internet Explorer

Firefox

Opera

Safari

Mozilla

<script>

var request...

function foo()

{

...

}

</script>

showConrmation()

8

This time, it’s the server

sending back a response.

PHP script

<?php

require(‘lib.php’);

function go() {

$myVar = ...

return ...

}

?>

The POST request

gets to the Break

Neck server.

POST request

placing order

Since this is a POST request,

the browser doesn’t look up any

responsees in its caching table. It

just sends the request on normally.

Browsers don’t try and

cache POST requests.

302

Chapter 5

questions

Frequently asked

?

Q:

Now that we’re using a POST request, does the length

of the data we send in the request matter?

a: No. You can send as much data in a POST request as you

like. So those big orders for your next bachelorette party will get

through to Break Neck with no problems.

Q:

Is the