JS language features that are implemented in the Mozilla JS engine are ordinarily safe to use in Mozilla code.
However, there are a few exceptions, listed here.
JS Language features
Proper tail calls are not implemented.
JS standard library features
| Feature | Standard | Can be used in code |
|---|---|---|
new Proxy(target, handler) |
ES2015 | Yes, but getPrototypeOf and setPrototypeOf handlers are not yet implemented. |
ArrayBuffer.transfer() |
proposed for ES2016 | No, Nightly-only for now |
SharedArrayBuffer, SharedInt8Array..., Atomics |
proposed for ES2016 | No, Nightly-only for now |
TypedObject |
proposed for ES2016 | No, Nightly-only for now |
SIMD |
proposed for ES2016 | No, Nightly-only for now |