files/en-us/web/javascript/reference/global_objects/math/f16round/index.md

metadata

title: Math.f16round()
short-title: f16round()
slug: Web/JavaScript/Reference/Global_Objects/Math/f16round
page-type: javascript-static-method
browser-compat: javascript.builtins.Math.f16round
sidebar: jsref

The Math.f16round() static method returns the nearest 16-bit half precision float representation of a number.

{{InteractiveExample("JavaScript Demo: Math.f16round()")}}

console.log(Math.f16round(5.5));
// Expected output: 5.5

console.log(Math.f16round(5.05));
// Expected output: 5.05078125

console.log(Math.f16round(5));
// Expected output: 5

console.log(Math.f16round(-5.05));
// Expected output: -5.05078125

Syntax

Math.f16round(doubleFloat)

Parameters

• doubleFloat
  • : A number.

Return value

The nearest 16-bit half precision float representation of doubleFloat.

Description

Math.f16round is the 16-bit counterpart of {{jsxref("Math.fround()")}}. It is intended to smooth some rough edges when interacting with float16 numbers, such as when reading from a {{jsxref("Float16Array")}}. Internally, JavaScript continues to treat the number as a 64-bit float, it just performs a "round to even" on the 10th bit of the mantissa, and sets all following mantissa bits to 0. If the number is outside the range of a 16-bit float, {{jsxref("Infinity")}} or -Infinity is returned.

Because f16round() is a static method of Math, you always use it as Math.f16round(), rather than as a method of a Math object you created (Math is not a constructor).

Examples

Using Math.f16round()

The number 1.5 can be precisely represented in the binary numeral system, and is identical in 16-bit and 64-bit:

Math.f16round(1.5); // 1.5
Math.f16round(1.5) === 1.5; // true

However, the number 1.337 cannot be precisely represented in the binary numeral system, so it differs in 16-bit and 64-bit:

Math.f16round(1.337); // 1.3369140625
Math.f16round(1.337) === 1.337; // false

100000 is too big for a 16-bit float, so Infinity is returned:

Math.f16round(100000); // Infinity

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• Polyfill of Math.f16round in core-js
• es-shims polyfill of Math.f16round
• {{jsxref("Math.fround()")}}
• {{jsxref("Math.round()")}}