Head Rush Ajax

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Chapter 5

Send OrderHTML Form PHP Script Callback

Now that you know how to get a response header from the server, you can

improve the Break Neck JavaScript, and let customers know a little more

about any errors they run into.

Let’s make a few simple changes to pizza.js:

Break Neck error handling

function showConrmation() {

if (request.readyState == 4) {

if (request.status == 200) {

var response = request.responseText;

var mainDiv = document.getElementById(“main-page”);

var orderForm = document.getElementById(“order-form”);

pElement = document.createElement(“p”);

textNode = document.createTextNode(

“Your order should arrive within “ +

response +

“ minutes. Enjoy your pizza!”);

pElement.appendChild(textNode);

mainDiv.replaceChild(pElement, orderForm);

} else {

var message = request.getResponseHeader(“Status”);

if ((message.length == null) || (message.length <= 0)) {

alert(“Error! Request status is “ + request.status);

} else {

alert(message);

}

}

}

}

OK, so

now

we’re ready to go, right?

If placeOrder.php reports an

error, the status code will

be “400”, so the “else” part

of this code will run.

This gets the value of the “Status”

response header, if there is one.

If the server or script returned a

“Status” response header, then show

that to the customer.

If there’s no “Status” response

header, then just print out the

error code, like we did in the older

versions ...