The byteLength accessor property represents the length (in bytes) of a typed array.




The byteLength property is an accessor property whose set accessor function is undefined, meaning that you can only read this property. The value is established when a TypedArray is constructed and cannot be changed. If the TypedArray is not specifying an byteOffset or a length, the length of the referenced ArrayBuffer will be returned. TypedArray is one of the TypedArray objects.


Using the byteLength property

var buffer = new ArrayBuffer(8);

var uint8 = new Uint8Array(buffer);
uint8.byteLength; // 8 (matches the byteLength of the buffer)

var uint8 = new Uint8Array(buffer, 1, 5);
uint8.byteLength; // 5 (as specified when constructing the Uint8Array)

var uint8 = new Uint8Array(buffer, 2);
uint8.byteLength; // 6 (due to the offset of the constructed Uint8Array)


Specification Status Comment
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'TypedArray.prototype.byteLength' in that specification.
Standard Initial definition.
ECMAScript 2017 Draft (ECMA-262)
The definition of 'TypedArray.prototype.byteLength' in that specification.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support 7.0 4.0 (2) 10 11.6 5.1
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support 4.0 (Yes) 4.0 (2) 10 11.6 4.2

See also

Document Tags and Contributors

 Contributors to this page: dchest, fscholz
 Last updated by: dchest,