Section 2.8. Event handlers connect HTML to JavaScript


2.8. Event handlers connect HTML to JavaScript

Remember event handlers from Chapter 1? You used the onClick handler to connect a button on an HTML page to a JavaScript function. Let's take a quick peek back at Chapter 1:

Remember this? We used event handlers to connect the "Show Me the Money" button in the Boards app to a JavaScript function.

We need to use one of these event handlers to connect the phone number field to a JavaScript function.

Aren't you getting a little ahead of things? How can we write an event handler if we haven't even written a JavaScript function yet?

2.8.1. Plan first, code later

Sometimes, it's better to do a little planning before you jump in and start writing code. In this case, we can go ahead and decide what we'll call the JavaScript function that makes a request to the Break Neck server, even though you haven't started coding it yet. Let's name this function getCustomerInfo(), since that's exactly what the function is going to do: ask the server for the customer's information.

And now that you know the name of this function, you can go ahead and update the HTML in the Break Neck form to run getCustomerInfo() when a phone number is entered... even though you won't code the function for a few more pages.

You might want to flip back to your application blueprints on page 73, and add the name of this JavaScript function to your notes.

Speaking of planning...

Looking for answers to the Be the Architect exercise back on page 73? You'll find them... throughout this entire chapter. As you read through the chapter, you'll see how we decided to build the Break Neck Pizza order app. See how your decisions match up with ours, and think about how you might do things differently.





Head Rush Ajax
Head Rush Ajax (Head First)
ISBN: 0596102259
EAN: 2147483647
Year: 2004
Pages: 241

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