April 2007
Intermediate to advanced
1728 pages
47h 51m
English
Content preview from JavaScript® Bible, Sixth 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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Chapter 50. Application: A Lookup Table
IN THIS CHAPTER
Serverless data collection lookup
Data-entry validation
One of the first ideas that intrigued me about JavaScript was the notion of delivering CGI-like functionality along with an HTML document. On the Web, numerous, small data collections currently require CGI scripting and a back-end database engine to drive them. Of course, not everyone who has information to share has access to the server environment (or the expertise) to implement such a solution. JavaScript provides that power.
A Serverless Database
Before you get too carried away with the idea of letting JavaScript take the place of your SQL database, you need to recognize several limitations that prevent JavaScript from being a universal solution. First, any database that you embed into an HTML document is read-only. Although you can script an interface and lookup routines for the user, no provisions are available for writing revised information back to the server, if that is your intention.
A second consideration is the size of the data collection. Unlike databases residing on servers, the entire JavaScript database (or subset you define for inclusion into a single HTML document) must be downloaded to the user's browser before the user can work with the data. As a point of reference, think about image files. At 56.6 Kbps through a dial-up connection, how large an image file would you tolerate downloading? Granted, a vast majority of users now have broadband access of some ...
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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.