arrayZip (#1150)

* arrayZip

* Update packages/util/src/array/zip.spec.ts

* Update packages/util/src/array/zip.ts

CHANGELOG.md

@@ -8,6 +8,7 @@ Contributed:
 
 Changes:
 
+- Add `arrayZip` to combine a key + value array into entries-like
 - Assert `chainCode` inputs to `derive*`, protecting against misuse
 - Adjust testnet detection in `@polkadot/networks`
 - Bump Ledger libraries to latest versions

packages/util/src/array/index.ts

@@ -10,3 +10,4 @@ export { arrayFilter } from './filter';
 export { arrayFlatten } from './flatten';
 export { arrayRange } from './range';
 export { arrayShuffle } from './shuffle';
+export { arrayZip } from './zip';

packages/util/src/array/zip.spec.ts

@@ -0,0 +1,24 @@
+// Copyright 2017-2021 @polkadot/util authors & contributors
+// SPDX-License-Identifier: Apache-2.0
+
+import { arrayZip } from '.';
+
+describe('arrayZip', (): void => {
+  it('zips a simple one', (): void => {
+    expect(
+      arrayZip(['a', 'b', 'c'], [1, 2, 3])
+    ).toEqual([['a', 1], ['b', 2], ['c', 3]]);
+  });
+
+  it('zips where values > keys', (): void => {
+    expect(
+      arrayZip(['a', 'b', 'c'], [1, 2, 3, 4])
+    ).toEqual([['a', 1], ['b', 2], ['c', 3]]);
+  });
+
+  it('zips where values < keys', (): void => {
+    expect(
+      arrayZip(['a', 'b', 'c'], [1, 2])
+    ).toEqual([['a', 1], ['b', 2], ['c', undefined]]);
+  });
+});

packages/util/src/array/zip.ts

@@ -0,0 +1,12 @@
+// Copyright 2017-2021 @polkadot/util authors & contributors
+// SPDX-License-Identifier: Apache-2.0
+
+export function arrayZip <K, V> (keys: K[], values: V[]): [K, V][] {
+  const result = new Array<[K, V]>(keys.length);
+
+  for (let i = 0; i < keys.length; i++) {
+    result[i] = [keys[i], values[i]];
+  }
+
+  return result;
+}