Head Rush Ajax

300

Chapter 5

Hold on a second... just because

we’re using a POST request, caching

isn’t an issue? I’d like a little more

explanation than that.

Browsers know exactly what data you’re

sending them in a GET request... all

the data is in the request URL. So when

the web browser thinks a request is the

same—because the same data is in the

URL—it tries to “help out” and return

any cached answer it has for that request.

Browsers cache GET requests

Web Browser

Internet Explorer

Firefox

Opera

Safari

Mozilla

<script>

var request...

function foo()

{

...

}

</script>

showConrmation()

Request URL

Server Response

placeOrder.php?phone=... 5

GET request

placing order

5

The browser thinks it’s helping you...

...but it ends up giving you the

same data over and over.

Even worse, the server NEVER

gets the new pizza order!

PHP script

<?php

require(‘lib.php’);

function go() {

$myVar = ...

return ...

}

?>

The request

never makes it

to the Break

Neck server.

Here’s the browser’s

caching table.

post requests aren’t cached