2.16. Creating a request object
This step is all about making a request to the Break Neck server. For that, we need a request object that our JavaScript function can use. Luckily, though, you already wrote code that creates a request object back in Chapter 1, in the createRequest()
function.
You should remember createRequest() from Chapter 1. Let's take a look at that JavaScript again, and make sure it's ready to use in the Break Neck app:
Here's the top part of pizza.html, updated with the createRequest()
function from Chapter 1.
<html>
<head>
<title>Break Neck Pizza Delivery</title>
<link rel="stylesheet" type="text/css" href="breakneck.css" />
<script language="javascript" type="text/javascript">
var request = null;
Since requset
isn't created inside a function,
all your functions can use the request variable.
function createRequest() {
try {
request = new XMLHttpRequest();
} catch (trymicrosoft) {
try {
request = new ActiveXObject("Msxml2.XMLHTTP");Remember, we had to use different
code for different browsers.
} catch (othermicrosoft) {
try {This was all pre-assembled JavaScript
in Chapter 1.We've pulled
this code out of its pre-assembled box... you're going to learn exactly what each
line of this JavaScript does over the next few pages.
request = new ActiveXObject("Microsoft.XMLHTTP");
} catch (failed) {
request = null;
}
}
}
if (request == null)
Our error checking here makes sure nothing went wrong.
alert("Error creating request object!");
}
function getCustomerInfo() {
var phone = document.getElementById("phone").value;
createRequest();
var url = "lookupCustomer.php?phone=" + escape(phone);
request.open("GET", url, true);
request.onreadystatechange = updatePage;
request.send(null);
}
</script>
</head>
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