Professional JavaScript | 38 | WebReference

Professional JavaScript | 38

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Professional JavaScript

EnReach Technologies

EnReach Technologies at www.enreach.com aren't a consumer electronics company like WebTV. Instead, they are one step further down the development chain. Their set-top browser is a development kit that other companies can purchase and embed in a set-top device. Several companies have already done this. Here's a screen shot of their browser environment at work:

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Unlike the WebTV pictures this is more like the actual TV image. Notice the lack of any form of navigation except icons and large text within the page - this really forces the Web page designer and client side scriptwriter to think about navigation.

Just like WebTV, the EnReach browser supports JavaScript to the Netscape 3.0 level. What's particularly interesting about this browser is that while some of its functionality is fixed, like the features that display HTML code and that do the Internet connection, others are not. In particular, the set-top browser is extendable - a developer embedding it in a set-top device can add other features like an e-mail client, a chat client or a news ticker for example. How are these features developed? In special JavaScript scripts which are put into the set-top box along with the browser. So not only can the browser act on JavaScript embedded in HTML pages, it is also partially made out of JavaScript scripts itself. Alas, this is far too narrow a field to get any further attention in this book.

Acorn

Finally in the set-top market, Acorn computers, developers of the Acorn PC also have a set-top browser with JavaScript support. See www.acorn.com for more details. Obviously, writing an HTML browser and adding JavaScript is not particularly difficult, and we can expect to see more variety still in JavaScript capable browsers in the future.

Really Different Browsers

A JavaScript enabled browser, whether in a PC or a set-top box, is nevertheless much the same thing. However, there are some even stranger places where JavaScript is found that we could still qualify as browsers, provided we broaden our minds a bit.

Adobe Acrobat

When people think of the PDF file format invented by Adobe, they usually think of a friendly, portable document format that can be used to display documents nicely and which provides good quality printouts. The Adobe Acrobat Reader is the free tool most people use for viewing PDF files.

However, the original design goals of the PDF format and the Acrobat Reader included some Web browser like features - hypertext links are the most obvious one, followed by incremental download from a remote site. However, the format also supports forms embedded in PDF documents. Where there's forms there's form data, and where there's form data there's user data entry mistakes and the need for validation. JavaScript code embedded in the document and an interpreter in the Reader software allows this validation to take place. You'll never see this JavaScript, unless you buy the full set of document preparation tools from Adobe - just Adobe Acrobat and Distiller isn't sufficient.

WAP

Our run down of JavaScript-enabled browsers wouldn't be complete without a nod of the head to WAP. What's a WAP? WAP stands for Wireless Application Protocol. The WAP consortium at www.wapforum.org is responsible for minting a collection of standards that will let users of handheld devices like PalmPilots and mobile phones access the Web.

At the end of these standards will be Web browsers inside handheld devices with very small resolution screens, probably black and white and with many variations from plain HTML. Where HTML goes, so goes JavaScript, except the WAP consortium aren't happy with the ECMAScript standard (they thought it was too big for a handheld device). Instead, they went off and defined WAPScript - a new standard for a cut-down tiny version of JavaScript that will run in your new satellite pocket calculator and other grown-up toys. Never fear ... testing your ordinary Web-based JavaScript script's compatibility against a Nokia mobile phone is not something you'll need to do in any hurry.

Thus completes our roundup of browsers supporting JavaScript.

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Created: April 12, 2001
Revised: April 12, 2001

URL: http://webreference.com/programming/javascript/professional/chap4/5/