Head Rush Ajax

308

Chapter 5

HTML Form PHP Script CallbackSend Order

You have to set the content type for your POST data before you send the request.

Then, when the request is sent, the server will get the request URL, the POST data,

and the type of data it should expect. Anytime you need to tell a server something

about a request, you’ll use a request header.

Let’s see how we can set a request header for the Break Neck request:

Setting the Content Type

function submitOrder() {

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

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

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

var url = “placeOrder.php”;

request.open(“POST”, url, true);

request.onreadystatechange = showConrmation;

request.setRequestHeader(“Content-Type”,

“application/x-www-form-urlencoded”);

request.send(“phone=” + escape(phone) +

“&address=” + escape(address) +

“&order=” + escape(order));

}

setRequestHeader()

allows you to add

information to the

request, usually

intended for use by

the server.

“Content-Type” is the

name of the header...

...and this is the value for

that request header.

This tells the server the data is encoded like

it would be in a request URL, just as if the

data came as part of a GET request.

Q:

So a request header is sent to the server along with

the request?

a: Yes. Any request headers are part of the request. In fact,

the web browser sets some ...