Head Rush Ajax

292

Chapter 5

Wait a second... doesn’t placeOrder.php return

an error message along with any error status

codes? If we show that error message to the

customer, they’ll know what went wrong.

Flip back to the placeOrder.php script

on page 284, and look at those lines at the

top that check and make sure the customer’s

address and pizza order were received. If

there’s a problem, the script returns a status

code of “400” along with an error message, and

stops processing the customer’s order.

But, our JavaScript callback,

showConrmation(), doesn’t check for an

error message from the script; it just shows the

request object’s HTTP status code if it’s not

200. That’s not very helpful...

Error messages are a good thing

Send OrderHTML Form PHP Script Callback

if (strlen($order) <= 0) {

header(“Status: No order was received.”, true, 400);

exit;

}

if (strlen($address) <= 0) {

header(“Status: No address was received.”, true, 400);

exit;

}

The PHP code creates a new response header:

“Status” becomes the name

of the response header

sent back to the browser.

Everything after “Status:“

becomes part of the message

returned as the value of the

response header.

This sends a status code of

“400”, and “true” means to

replace any existing response

headers with the same type;

in this case, that’s “Status”.

response headers