petamoriken / proposal-float16array

a proposal to add float16 TypedArrays to JavaScript

Float16Array

A proposal to add float16 (aka half-precision or binary16) TypedArrays to JavaScript.

Status

Authors: Kevin Gibbons

Champions: Leo Balter

This proposal is at Stage 1 of The TC39 Process.

Spec text is available here.

Motivation

• Explicit request from the Color on the Web CG, for their use case with float-backed canvases.
• Useful for GPU operations, where full precision often isn't necessary and memory constraints are serious.
  • WebGPU supports float16. It exposes/consumes raw ArrayBuffers. When those contain 32-bit floats, the pattern is to wrap the buffer in new Float32Array(...); that doesn't work when they contain 16-bit floats.
  • Increasingly relevant with new tools like Stable Diffusion, where full-precision representations don't fit in VRAM on many machines.
• Faking it in userland has serious performance costs.

Proposal

This would add a new kind of TypedArray, Float16Array, to complement the existing Float32Array and Float64Array. It would also add two new methods on DataView for reading and setting float16 values, as getFloat16 and setFloat16, to complement the existing similar methods for working with full and double precision floats.