typed-array-byte-offset

Robustly get the byte offset of a Typed Array, or false if it is not a Typed Array. Works cross-realm, in every engine, even if the byteOffset property is overridden.

Example

var typedArrayByteOffset = require('typed-array-byte-offset');
var assert = require('assert');

assert.equal(false, typedArrayByteOffset(undefined));
assert.equal(false, typedArrayByteOffset(null));
assert.equal(false, typedArrayByteOffset(false));
assert.equal(false, typedArrayByteOffset(true));
assert.equal(false, typedArrayByteOffset([]));
assert.equal(false, typedArrayByteOffset({}));
assert.equal(false, typedArrayByteOffset(/a/g));
assert.equal(false, typedArrayByteOffset(new RegExp('a', 'g')));
assert.equal(false, typedArrayByteOffset(new Date()));
assert.equal(false, typedArrayByteOffset(42));
assert.equal(false, typedArrayByteOffset(NaN));
assert.equal(false, typedArrayByteOffset(Infinity));
assert.equal(false, typedArrayByteOffset(new Number(42)));
assert.equal(false, typedArrayByteOffset('foo'));
assert.equal(false, typedArrayByteOffset(Object('foo')));
assert.equal(false, typedArrayByteOffset(function () {}));
assert.equal(false, typedArrayByteOffset(function* () {}));
assert.equal(false, typedArrayByteOffset(x => x * x));
assert.equal(false, typedArrayByteOffset([]));

const buffer = new ArrayBuffer(32);

assert.equal(8, typedArrayByteOffset(new Int8Array(buffer, 8)));
assert.equal(8, typedArrayByteOffset(new Uint8Array(buffer, 8)));
assert.equal(8, typedArrayByteOffset(new Uint8ClampedArray(buffer, 8)));
assert.equal(4, typedArrayByteOffset(new Int16Array(buffer, 4)));
assert.equal(4, typedArrayByteOffset(new Uint16Array(buffer, 4)));
assert.equal(8, typedArrayByteOffset(new Int32Array(buffer, 8)));
assert.equal(8, typedArrayByteOffset(new Uint32Array(buffer, 8)));
assert.equal(16, typedArrayByteOffset(new Float32Array(buffer, 16)));
assert.equal(16, typedArrayByteOffset(new Float64Array(buffer, 16)));
assert.equal(16, typedArrayByteOffset(new BigInt64Array(buffer, 16)));
assert.equal(16, typedArrayByteOffset(new BigUint64Array(buffer, 16)));

Tests

Simply clone the repo, npm install, and run npm test