IEEE 754 half-precision floating-point ponyfill for JavaScript
See TC39 proposal or the archive of the ES Discuss Float16Array topic for details
npm install @petamoriken/float16Note
Native float16 features are supported since Deno v1.43.
deno add jsr:@petamoriken/float16Note
Native float16 features are supported since Bun v1.1.23.
bun add @petamoriken/float16import {
Float16Array, isFloat16Array, isTypedArray,
getFloat16, setFloat16,
f16round,
} from "@petamoriken/float16";Deliver a browser/float16.mjs or browser/float16.js file in the npm package
from your Web server with the JavaScript Content-Type HTTP header.
<!-- Module Scripts -->
<script type="module">
import {
Float16Array, isFloat16Array, isTypedArray,
getFloat16, setFloat16,
f16round,
} from "DEST/TO/float16.mjs";
</script><!-- Classic Scripts -->
<script src="DEST/TO/float16.js"></script>
<script>
const {
Float16Array, isFloat16Array, isTypedArray,
getFloat16, setFloat16,
f16round,
} = float16;
</script>Or, you can use jsDelivr CDN.
<!-- Module Scripts -->
<script type="module">
import {
Float16Array, isFloat16Array, isTypedArray,
getFloat16, setFloat16,
f16round,
} from "https://cdn.jsdelivr.net/npm/@petamoriken/float16/+esm";
</script><!-- Classic Scripts -->
<script src="https://cdn.jsdelivr.net/npm/@petamoriken/float16/browser/float16.min.js"></script>
<script>
const {
Float16Array, isFloat16Array, isTypedArray,
getFloat16, setFloat16,
f16round,
} = float16;
</script>This package only requires ES2015 features and does not use
environment-dependent features (except for inspect/), so you can use it
without any problems. It works fine with
the current officially supported versions of Node.js.
Float16Array implemented by Proxy and Reflect, so IE11 is never supported
even if you use polyfills.
lib/ and browser/ directories in the npm package have JavaScript files
already transpiled, and they have been tested automatically in the following
environments:
- Node.js: Active LTS
- Firefox: last 2 versions and ESR
- Chrome: last 2 versions
- Safari: last 2 versions
Float16Array is similar to TypedArray such as Float32Array
(MDN).
const array = new Float16Array([1.0, 1.1, 1.2, 1.3]);
for (const value of array) {
// 1, 1.099609375, 1.2001953125, 1.2998046875
console.log(value);
}
// Float16Array(4) [ 2, 2.19921875, 2.3984375, 2.599609375 ]
array.map((value) => value * 2);Warning
This API returns false for ECMAScript's native Float16Array
isFloat16Array is a utility function to check whether the value given as an
argument is an instance of Float16Array or not.
const buffer = new ArrayBuffer(256);
// true
isFloat16Array(new Float16Array(buffer));
// false
isFloat16Array(new Float32Array(buffer));
isFloat16Array(new Uint16Array(buffer));
isFloat16Array(new DataView(buffer));isTypedArray is a utility function to check whether the value given as an
argument is an instance of a type of TypedArray or not. Unlike
util.types.isTypedArray in Node.js, this returns true for Float16Array.
const buffer = new ArrayBuffer(256);
// true
isTypedArray(new Float16Array(buffer));
isTypedArray(new Float32Array(buffer));
isTypedArray(new Uint16Array(buffer));
// false
isTypedArray(new DataView(buffer));getFloat16 and setFloat16 are similar to DataView methods such as
DataView#getFloat32
(MDN)
and DataView#setFloat32
(MDN).
declare function getFloat16(view: DataView, byteOffset: number, littleEndian?: boolean): number;
declare function setFloat16(view: DataView, byteOffset: number, value: number, littleEndian?: boolean): void;const buffer = new ArrayBuffer(256);
const view = new DataView(buffer);
view.setUint16(0, 0x1234);
getFloat16(view, 0); // 0.0007572174072265625
// You can append methods to DataView instance
view.getFloat16 = (...args) => getFloat16(view, ...args);
view.setFloat16 = (...args) => setFloat16(view, ...args);
view.getFloat16(0); // 0.0007572174072265625
view.setFloat16(0, Math.PI, true);
view.getFloat16(0, true); // 3.140625f16round is similar to Math.fround
(MDN).
This function returns nearest half-precision float representation of a number.
declare function f16round(x: number): number;Math.fround(1.337); // 1.3370000123977661
f16round(1.337); // 1.3369140625Float16Array has some limitations, because it is impossible to completely reproduce the behavior of TypedArray. Be careful when checking if it is a TypedArray or not by using ArrayBuffer.isView, and when using Web standards such as structuredClone and WebGL.
Built-in TypedArray objects use "internal slots" for built-in methods. Some
limitations exist because the Proxy object can't trap internal slots
(explanation).
This package isn't polyfill, in other words, it doesn't change native global functions and static/prototype methods.
E.g. ArrayBuffer.isView is the butlt-in method that checks if it has the
[[ViewedArrayBuffer]] internal slot. It returns false for Proxy object
such as Float16Array instance.
ArrayBuffer.isView(new Float32Array(10)); // true
ArrayBuffer.isView(new Float16Array(10)); // falseThe structured clone algorithm copies complex JavaScript objects. It is used
internally when invoking structuredClone(), to transfer data between Web
Workers via postMessage(), storing objects with IndexedDB, or copying objects
for other APIs
(MDN).
It can't clone Proxy object such as Float16Array instance, you need to
convert it to Uint16Array or deal with ArrayBuffer directly.
const array = new Float16Array([1.0, 1.1, 1.2]);
const cloned = structuredClone({ buffer: array.buffer });WebGL requires Uint16Array for buffer or texture data whose types are
gl.HALF_FLOAT (WebGL 2) or ext.HALF_FLOAT_OES (WebGL 1 extension). Do not
apply the Float16Array object directly to gl.bufferData or gl.texImage2D
etc.
// WebGL 2 example
const vertices = new Float16Array([
-0.5, -0.5, 0,
0.5, -0.5, 0,
0.5, 0.5, 0,
]);
const buffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
// wrap in Uint16Array
gl.bufferData(gl.ARRAY_BUFFER, new Uint16Array(vertices.buffer), gl.STATIC_DRAW);
gl.vertexAttribPointer(location, 3, gl.HALF_FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, null);
gl.enableVertexAttribArray(location);See JSDoc comments in src/Float16Array.mjs for details. If you don't write
hacky code, you shouldn't have any problems.
Provides custom inspection for Node.js and Deno, which makes the results of console.log more readable.
import { Float16Array } from "@petamoriken/float16";
import { customInspect } from "@petamoriken/float16/inspect";
Float16Array.prototype[Symbol.for("nodejs.util.inspect.custom")] = customInspect;import { Float16Array } from "@petamoriken/float16";
import { customInspect } from "@petamoriken/float16/inspect";
// deno-lint-ignore no-explicit-any
(Float16Array.prototype as any)[Symbol.for("nodejs.util.inspect.custom")] = customInspect;Manual build and test
This repository uses corepack for package manager manager. You may have to activate yarn in corepack.
corepack enable yarnDownload devDependencies.
yarnBuild lib/, browser/ files.
yarn run buildBuild docs/ files (for browser test).
yarn run docsThis repository uses corepack for package manager manager. You may have to activate yarn in corepack.
corepack enable yarnDownload devDependencies.
yarnNODE_ENV=test yarn build:lib
yarn testNODE_ENV=test yarn build:browser
yarn docsAccess docs/test/index.html with browsers.
You can access current test page
(power-assert version) in
master branch.
MIT License
This software contains productions that are distributed under
the Apache 2.0 License.
Specifically, index.d.ts is modified from the original
TypeScript lib files.
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