Why JavaScript On Mobile Is Slow

An anonymous reader writes "Drew Crawford has a good write up of the current state of JavaScript in mobile development, and why the lack of explicit memory handling (and a design philosophy that ignores memory issues) leads to massive garbage collection overhead, which prevents HTML5/JS from being deployed for anything besides light duty mobile web development. Quoting: 'Here’s the point: memory management is hard on mobile. iOS has formed a culture around doing most things manually and trying to make the compiler do some of the easy parts. Android has formed a culture around improving a garbage collector that they try very hard not to use in practice. But either way, everybody spends a lot of time thinking about memory management when they write mobile applications. There’s just no substitute for thinking about memory. Like, a lot. When JavaScript people or Ruby people or Python people hear "garbage collector," they understand it to mean "silver bullet garbage collector." They mean "garbage collector that frees me from thinking about managing memory." But there’s no silver bullet on mobile devices. Everybody thinks about memory on mobile, whether they have a garbage collector or not. The only way to get "silver bullet" memory management is the same way we do it on the desktop–by having 10x more memory than your program really needs.'"

Comments

That's just not a viable option.

[Anonymous Coward]

Since JavaScript is so damn lacking, those libraries are ESSENTIAL for anything beyond the smallest JavaScript app.

Even if you don't use jQuery, for example, you're going to need to find and then use some other library that does the same thing, or write a whole shitload of code yourself to implement the same functionality. Zepto works as an alternative for some people, but even it still has some overhead.

That applies to almost anything you want your app to do. If you want to work with objects, arrays or even strings in any way beyond the simplest of manipulations, you're going to need to use some third-party code, or write a whole lot of it yourself.

JavaScript developers are so wholly dependent on these third-party libraries because the JavaScript implementations themselves are so bloody lacking. It's totally different than a language like Python, where there's a rich, yet still compact and efficient, standard library that developers know will be available on just about every user's system. JavaScript programmers have to provide this basic infrastructure with each and every app they write.