TypedArray.prototype.length
BaselineWidely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
Thelength accessor property ofTypedArray instances returns the length (in elements) of this typed array.
Try it
// Create an ArrayBuffer with a size in bytesconst buffer = new ArrayBuffer(8);const uint8 = new Uint8Array(buffer, 2);console.log(uint8.length);// Expected output: 6Description
Thelength property is an accessor property whose set accessor function isundefined, meaning that you can only read this property. The value is established when aTypedArray is constructed and cannot be changed. If theTypedArray is not specifying abyteOffset or alength, the length of the referencedArrayBuffer will be returned.TypedArray is one of theTypedArray objects.
Examples
Using thelength property
js
const buffer = new ArrayBuffer(8);let uint8 = new Uint8Array(buffer);uint8.length; // 8 (matches the length of the buffer)uint8 = new Uint8Array(buffer, 1, 5);uint8.length; // 5 (as specified when constructing the Uint8Array)uint8 = new Uint8Array(buffer, 2);uint8.length; // 6 (due to the offset of the constructed Uint8Array)Specifications
| Specification |
|---|
| ECMAScript® 2026 Language Specification # sec-get-%typedarray%.prototype.length |