Head Rush Ajax

114

Chapter 2

When you’re writing synchronous

applications, you can usually put your elds

on a form in whatever order you like. But for

synchronous applications like Break Neck,

you’re going to have to think a little harder

about how your form should look.

In the Break Neck order form, you probably

don’t want customers to start entering their

address, and then have your callback function

overwrite that with the address from the

server. Instead, let’s re-order the form, so

customers go from the phone number eld to

the order eld. That way, customers can start

entering their pizza order while their address

is being looked up.

Order matters in asynchronous apps

I was typing in my address before

updatePage() got a response and lled it

in. That seems sort of confusing... and

annoying! Can’t we x that?

Go ahead and ip

these two elds in

your pizza.html le.

Now customers will enter their

order after typing in their

phone number. By the time

they’re done, their address

will have already appeared.

Man, Break Neck pizza rocks. There’s

nothing like a breakfast of cold pizza, a

whipped latte from Starbuzz, and the

Webville Times to read.

<script>

var request...

function foo()

{

...

}

</script>

JavaScript

<script>

var request...

function foo()

{

...

}

</script>

Customer’s Phone Number

Customer’s Address

Customer’s Order

changing the user interface