feat: Add a function to concat typed arrays into one Uint8Array (#13)

src/byte-helpers.js

@@ -44,3 +44,26 @@ export const stringToBytes = (string, stringIsBytes = false) => {
 
  return string.split('').map((s) => s.charCodeAt(0) & 0xFF);
 };
+
+export const concatTypedArrays = (...buffers) => {
+ const totalLength = buffers.reduce((total, buf) => {
+ const len = buf && (buf.byteLength || buf.length);
+
+ total += len || 0;
+
+ return total;
+ }, 0);
+
+ const tempBuffer = new Uint8Array(totalLength);
+
+ let offset = 0;
+
+ buffers.forEach(function(buf) {
+ buf = toUint8(buf);
+
+ tempBuffer.set(buf, offset);
+ offset += buf.byteLength;
+ });
+
+ return tempBuffer;
+};

test/byte-helpers.test.js

@@ -1,5 +1,10 @@
 import QUnit from 'qunit';
-import {bytesToString, stringToBytes, toUint8} from '../src/byte-helpers.js';
+import {
+ bytesToString,
+ stringToBytes,
+ toUint8,
+ concatTypedArrays
+} from '../src/byte-helpers.js';
 import window from 'global/window';
 
 const arrayNames = [];
@@ -85,3 +90,49 @@ QUnit.test('should function as expected', function(assert) {
  assert.ok(uint instanceof Uint8Array && uint.length > 0, `converted ${name} to Uint8Array`);
  });
 });
+
+QUnit.module('concatTypedArrays');
+
+QUnit.test('should function as expected', function(assert) {
+ const tests = {
+ undef: {
+ data: concatTypedArrays(),
+ expected: toUint8([])
+ },
+ empty: {
+ data: concatTypedArrays(toUint8([])),
+ expected: toUint8([])
+ },
+ single: {
+ data: concatTypedArrays([0x01]),
+ expected: toUint8([0x01])
+ },
+ array: {
+ data: concatTypedArrays([0x01], [0x02]),
+ expected: toUint8([0x01, 0x02])
+ },
+ uint: {
+ data: concatTypedArrays(toUint8([0x01]), toUint8([0x02])),
+ expected: toUint8([0x01, 0x02])
+ },
+ buffer: {
+ data: concatTypedArrays(toUint8([0x01]).buffer, toUint8([0x02]).buffer),
+ expected: toUint8([0x01, 0x02])
+ },
+ manyarray: {
+ data: concatTypedArrays([0x01], [0x02], [0x03], [0x04]),
+ expected: toUint8([0x01, 0x02, 0x03, 0x04])
+ },
+ manyuint: {
+ data: concatTypedArrays(toUint8([0x01]), toUint8([0x02]), toUint8([0x03]), toUint8([0x04])),
+ expected: toUint8([0x01, 0x02, 0x03, 0x04])
+ }
+ };
+
+ Object.keys(tests).forEach(function(name) {
+ const {data, expected} = tests[name];
+
+ assert.ok(data instanceof Uint8Array, `obj is a Uint8Array for ${name}`);
+ assert.deepEqual(data, expected, `data is as expected for ${name}`);
+ });
+});