Float16Array is a new type of array in JavaScript that stores 16-bit (2-byte) floating point numbers. It joins the existing family of TypedArrays like Int8Array, Uint8Array, Float32Array, and Float64Array

If you’ve never used TypedArrays before, think of them as specialized arrays that can only contain specific types of numbers.

Unlike regular JavaScript arrays that can mix strings, objects, and numbers, TypedArrays are fixed-size, memory-efficient arrays dedicated to numeric data.

Here’s how you’d create and use a Float16Array

1
// Create a Float16Array with 4 elements
2
const myArray = new Float16Array(4);
3

4
myArray[0] = 1.5;
5
myArray[1] = 42.0;
6
myArray[2] = 0.333;
7
myArray[3] = -27.5;
8

9
console.log(myArray); // Float16Array [1.5, 42, 0.3330078125, -27.5]

Notice something interesting with the third value? 0.333 became 0.3330078125. This happens because 16-bit floating point numbers have limited precision compared to JavaScript’s standard 64-bit numbers.

You might wonder: “We already have Float32Array and Float64Array, so why do we need a 16-bit version?”

The answer comes down to three things: memory, performance, and compatibility.

A Float16Array uses half the memory of a Float32Array. If you’re working with large datasets, this can make a significant difference.

For applications processing millions of values, this memory saving can be crucial. In certain contexts, especially with GPU-accelerated computing, 16-bit floats can be processed more efficiently than 32-bit or 64-bit numbers. Newer GPUs often have specialized hardware for handling 16-bit floating point math, making operations potentially faster.

References

• TC39 Float16Array
• Float16Array Proposal