"asm" entries

JavaScript shares its ubiquity

WebAssembly changes the rules of the JavaScript game.


I’ve never seen a technology lay down its primary advantage and prepare to hand over its ubiquity. I’m proud of JavaScript for doing this, and I’m sure that in the long run this will be good for the Web, but in the meantime I’m wondering where WebAssembly will take us.

Brendan Eich’s announcement of the effort makes clear that this builds on the earlier asm.js (and Google’s similar PNaCl), a highly efficient JavaScript subset that compilers of other languages could target. Eich enjoyed using Unreal Engine for demos of the speed asm.js could provide, but compiling to JavaScript, even weird JavaScript, still needed to go through a JavaScript parser. (Other approaches compiled to more comprehensible but less optimized JavaScript.)

WebAssembly – wasm – skips that final step, producing a binary format, technically a compressed AST encoding. Unless you’re going to be building compilers, you can compare wasm to a bytecode system. There is a text format for debugging, but the binary emphasis yields substantial extra speed as it skips parsing and minimizes decompression.
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