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From LiveScript® to JavaScript®

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A Programming Language for Client-Side Events

Using JavaScript® On the Web

JavaScript has become an integral part of most Web sites. But, of all you see happening on your Web page, what is JavaScript? (Certainly, the floating icons you may see floating over this page are controlled by JavaScript. But it also serves more serious purposes for Web sites.)

But, first, of all, let me tell you what JavaScript isn't:

  • It's not Java. Java® is a "write-once, use anywhere" platform neutral development language from Sun Microsystems. Java can be written to be launched by the browser (client-side) or, increasingly, as a tool from the server. Java can create self-launching, stand-alone applets.
  • It's not GIF animations. A lot of graphic files that go through animated sequences are GIF images strung together as one file, with timed intervals for their sequences. If you want to do the same thing, but with JPEG images, then you probably must script each image to change places using a JavaScript.
  • It's not JScript® — although JScript is almost JavaScript, just Microsoft's Visual Basic® imitation or adaptation of it. A European technical specification – ECMAScript® — is very similar to JavaScript. It's just, more or less, an Open Source standard variant of JavaScript.

Scripted Beginnings
JavaScript began life under the development wings of Netscape Communications during the mid-1990s. And, in its early days, it was called LiveScript® Netscape simply chose to let it ride on the marketing coattails of Java by calling it JavaScript — even though it shares nothing in technology or written code with Java.

Also unlike Java, which can be used as a strong server-side technology, JavaScript must be interpreted by the Web browser. So it is strictly a client-side technology.

However, if you serve up web pages under a Web-hosting plan that does not include CGI access, then a lot of the webmaster-to-enduser and special "service" capabilities must then use JavaScript.

Because JavaScript is interpreted by the browser, it adds overhead to a page. It is, therefore, important to use JavaScripts that aren't needlessly complex, less load times increase appreciably. Like everything else on the page, the browser must interpret and render it line-by-line. You will likely notice that this page loads much slower and renders a bit different than the other pages. That's because the "falling and dancing text" JavaScript used at the top of this page is lengthy and complex, and takes a toll on the rest of the page.

->TIP: Want to turn off the JavaScript on a page to access, for example, the object of a JavaScript rollover that disappears when you roll over or click on it?
With Internet Explorer, go to the Edit menu's Preferences and under Web Browser->Web Content, check "Enable Scripting." In Netscape, go to the Edit->Preferences->Advanced, check "Enable JavaScript."