Learning the iOS 4 SDK for JavaScript Programmers

More Access to the Hardware

It doesn’t take long to learn that web pages developed for general-purpose web browsers are encumbered with many restrictions. For example, a web page does not have free rein over the host computer’s filesystem, making it impossible for well-meaning scripts to read or write files on the hard disk (except for closely monitored dedicated files for items such as cookies and HTML5 data storage). JavaScript is granted very limited access to even the host browser’s environment or settings. Despite the possible convenience afforded by automatically adding the current web page to a user’s bookmarks list, such access is out of bounds for web pages.

All of these restrictions, of course, are imposed for the sake of security and privacy. Left unfettered, a script on a malicious hacker’s website could wreak havoc on every browser that lands at the site. Not many users would like unknown computers reading their recent browser histories or replacing system files with ones that could cause banking website visits to be redirected to lookalike phony sites that capture usernames and passwords. Cyber crooks are constantly on the prowl for vulnerabilities in popular browsers that they can exploit without the user’s knowledge—the so-called drive-by attacks that have plagued various browsers through the years.

An application designed to run natively on popular desktop computer operating systems, on the other hand, typically has exceptionally broad freedom to rummage around the ...