May 2011
Beginner
584 pages
17h 42m
English
Content preview from Creating a Website: The Missing Manual, 3rd EditionBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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JavaScript 101
Now that you’ve learned a bit about JavaScript and why it exists, it’s time to dive in and start creating your first real script.
The <script> Element
Every script starts with a <script> block you slot somewhere into an HTML document. Really, you have only two options:
The <body> section. Put scripts you want your browser to run right away in the <body> section of your HTML. The browser runs your script as soon as it reaches the <script> element. If you put your script at the beginning of the <body> section, your browser processes the script before it displays the page.
Tip
Usually, JavaScript fans put their scripts at the end of the <body> section. That way, you avoid errors that might occur if you use a script that relies on another part of the page, and the browser hasn’t read that section yet. Because browsers read an entire page quickly, these scripts execute almost immediately.
The <head> section. If you place an ordinary script in the <head> section of your HTML document, it runs immediately, before the browser processes any part of the markup. However, it’s more common to use the <head> section for scripts that contain functions (see Functions). Functions don’t run immediately—instead, you summon them when your visitor takes some kind of action on a page, like moving a mouse.
Note
You can place as many <script> blocks in a web page as you want.
A typical script block consists of a series of programming instructions. To get a handle on how these instructions work, consider ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.