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WebAssembly and the Future of JavaScript
Nerval's Lobster writes: WebAssembly is the next stage in the evolution of client-side scripting. In theory, it will improve on JavaScript's speed. That's not to say that JavaScript is a slowpoke: Incremental speed improvements have included the rollout of asm.js (an optimized subset) in 2013. But WebAssembly—while not a replacement for JavaScript—is intended as a "cure" for a variety of issues where JavaScript isn't always a perfect fit, including video editing, encryption, peer-to-peer, and more. (Here's a full list of the Web applications that WebAssembly could maybe improve.) If WebAssembly is not there to replace JavaScript but to complement it, the key to the integration rests with the DOM and Garbage Collected Objects such as JavaScript strings, functions (as callable closures), Typed Arrays and Typed objects. The bigger question is, will WebAssembly actually become something big, or is it ultimately doomed to suffer the fate of other hyped JavaScript-related platforms such as Dart (a Google-only venture), which attracted buzz ahead of a Minimum Viable Product release, only to quickly fade away afterward?
Previous attempts at replacing JavaScript always suffered from a boot strapping problem. While there are only a small number of major desktop browsers, overall, there are actually a lot of different minor browsers that people expect to work. And even among the desktop browsers, not everybody always runs the most recent release.
Content producers don't really like writing content that only 30% of their users can view. So, unless a new technology is rolled out to 90+% of the deployed browsers, nobody is going to write content for it. On the other hand, if nobody writes content, the rest of the browser manufacturers won't put any resources into adding support for the new technology.
Both asm.js and WebAssembly have a fallback mode that uses plain JavaScript, as available in virtually 100% of all browsers. Performance will obviously be degraded, but that's much better than making the content completely inaccessible. And users are more likely to upgrade their browsers, if they can see a low-fidelity version of the content and know by switching to a newer browser they'll get the high-fidelity version. So, unlike the previous scenario, this is actually a virtuous circle.
Might as well read an interview with the man behind webassembly. Found it extremely informative and I'm looking forward to a future where all major browsers support first-class alternatives to javascript through webassembly.
That is possibly true, although details will still need to be seen. asm.js programs typically allocate a single static memory region that they than manage themselves without bothering the JavaScript VM to track memory references. In fact, a asm.js program doesn't have access to garbage collected objects. As soon as it tries to access those, it falls back to JavaScript mode (every asm.js program is by definition also a valid JavaScript program, but not necessarily vice versa).
WebAssembly programs at least originally will do the same as asm.js. It is possible that as more experienced is gained with this feature, there will be a way for WebAssembly to tap into the garbage collected pool of objects. Only time will tell.