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Performance. WebAssembly has no JIT stage, it gets AOT compiled straight to machine code. Plus, it gives (or will give) much lower-level access to features like

Performance. WebAssembly has no JIT stage, it gets AOT compiled straight to machine code. Plus, it gives (or will give) much lower-level access to features like threads and memory allocation.

kllrnohj 9y ago
> Plus, it gives (or will give) much lower-level access to features like threads and memory allocation. There's no reason JavaScript couldn't just have those features. It already has some amount of memory allocation control via ArrayBuffer & DataView.
- imtringued 9y ago
  You're describing asm.js which had significant issues as a compilation target. The generated javascript code was massive and it took several seconds just to parse it.
  - caseymarquis 9y ago
    Related is a mozilla post on streaming wasm for big performance gains: https://hacks.mozilla.org/2018/01/making-webassembly-even-faster-firefoxs-new-streaming-and-tiering-compiler/ https://hacks.mozilla.org/2018/01/making-webassembly-even-fa...
  - kllrnohj 9y ago
    asm.js never added threads, which is a far bigger performance issue than fine-grained manual memory allocation is.
amaranth 9y ago
Thanks to Spectre I don't think we'll be seeing threads anytime soon. Well, not threads with shared memory anyway which removes a lot of the point of them. Same reason JavaScript just lost SharedArrayBuffer, too easy to make a high precision timer out of it.