Head Rush Ajax

142

Chapter 3

function getCustomerInfo() {

var phone = document.getElementById(“phone”).value;

var url = “lookupCustomer.php?phone=” + escape(phone);

request.open(“GET”, url, true);

request.onreadystatechange = updatePage;

request.send(null);

}

function updatePage() {

if (request.readyState == 4) {

if (request.status == 200) {

var customerAddress = request.responseText;

document.getElementById(“address”).value = customerAddress;

}

}

}

Here’s where we send the request

to the Break server.

Customer’s

Phone Number

Break Neck Pizza is an asynchronous app

Take another look at the Break Neck Pizza Ajax application. You type in your phone number,

and then move to the pizza order or address. The page’s JavaScript then gets your phone

number from the form, and sends the request for your address to the web server. If your

address takes a long time to look up, you’ll notice that you can go ahead and enter your pizza

order without having to wait for the server to return your address.

And here’s the callback function

that’s run when the response

comes back from the server.

Since this is an asynchronous request, from

the time the browser sends the request

to get your address to the time it gets a

response, you can still go on using the web

page. You won’t be stuck.

Remember, this parameter is how

you tell the request object to send

your request asynchronously.

Customer’s

Address and Order

Here’s the ...