Head Rush Ajax

26

Chapter 1

Initializing the connection

You’ve got a request object, and a variable with the URL to connect to.

Now you just need to tell the request object how to connect to the server,

and give it that URL as the address to connect to. Here’s how you do that:

Q:

I thought that it was better to use

“POST” for web page requests.

A: POST is usually used when you are

sending a server lots of data, or are completing

a form submit that involves money, or placing

an order. Since we’re not sending any data to

the PHP script, and there’s no purchase being

made here. it’s easier to use a GET request;

we’ll look at POST requests a little later on.

Q:

Should I ever use open() to make a

synchronous request, and set that last value

to “false”?

A: Sure. Sometimes you don’t want the user

to be able to keep using your page while the

server is answering a request. For instance, if

a user is placing an order, you probably don’t

want to let them do anything else until you

confirm that their order was accepted.

questions

Frequently asked

?

Let’s break that down a bit...

request.open(

“GET”,

url,

true);

The open()

method initializes

a connection...

...and then “GET” indicates how

to send data to the server.

This is the URL for the

PHP script running on

Katie’s web server.

This means that the request should

be asynchronous... in other words,

this lets JavaScript know that it

doesn’t need to wait around for a

resp