I don't understand event handling, any resources?

I would recommend buying this book.

It's a great book for beginners and advanced learners, also design and the layout of the book makes it perfect for future reference.

John, it may be helpful to just put it in context and ask specific questions about the topic. Event Handling is a broad topic. However, to put it into simple terms, it's basically a combination of something that happens at a single point in time that has a cause and effect type of reaction. Events are almost infinite in the world of computer programming.

For example, some events might be the following:

• A page loading
• A timer reaches zero
• A user hits the ESC button
• A user clicks the X on a window
• The mouse is moved two inches

The common factor in all of these is that it's something happening at a specific point in time.

Usually, it's important because the event will be used to trigger something.

For example, when a page loads, you may want code to execute a popup window. When a timer reaches zero, you may want something to print. When a user hits the ESC button, you may want to close a dialog box. Lastly, when a user clicke on the X on a window, you may want something to disappear.

Hope this helps!

Hi John,

I have the same questions as you, I'm trying to get my head wrapped around asynchronous programming (AKA 'non-blocking' or 'event-driven').

I am making my way through this tutorial: http://book.mixu.net/node/ch7.html

If you have not already, install Node.js on your platform and get on a first-name basis with it. I've had it installed for less than a week and am already learning a lot. What I'm learning is that there is a little worker inside Javascript (the Event Loop) that is busy responding to events on the message queue. So the way we write code will be partially procedural, and partially declarative. We have to imagine the Event Loop ticking away, and things we ask for vs things we receive being disjoint in time.

The basic basic idea is: Javascript is a language for handling complex I/O, not massive computation. And I/O is millions of time slower than computation. Imagine turning the page of a book, vs asking your assistant to load up a pack mule and travel for a month over a mountain range to visit a library and get a book for you. Similar order of magnitude. So you can get a lot of other work done while you're waiting. When your servant arrives, he rings the doorbell. You say, "Who is it?" He answers, "It's me, Callback!" Now you're ready to work on projects depending on the arrival of that book.

Take care, good luck!

-- Cal