Add arrayUnzip (#1598)

packages/util/src/array/index.ts

@@ -10,4 +10,5 @@ export { arrayFilter } from './filter';
 export { arrayFlatten } from './flatten';
 export { arrayRange } from './range';
 export { arrayShuffle } from './shuffle';
+export { arrayUnzip } from './unzip';
 export { arrayZip } from './zip';

packages/util/src/array/shuffle.ts

@@ -5,7 +5,7 @@
  * @name arrayShuffle
  * @description Shuffles the input array (unlike sort, this is not done in-place)
  */
-export function arrayShuffle <T> (input: T[]): T[] {
+export function arrayShuffle <T> (input: readonly T[]): T[] {
   const result = input.slice();
   let curr = result.length;
 

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

@@ -0,0 +1,12 @@
+// Copyright 2017-2022 @polkadot/util authors & contributors
+// SPDX-License-Identifier: Apache-2.0
+
+import { arrayUnzip } from '.';
+
+describe('arrayUnzip', (): void => {
+  it('unzips entries', (): void => {
+    expect(
+      arrayUnzip([['a', 1], ['b', 2], ['c', 3]])
+    ).toEqual([['a', 'b', 'c'], [1, 2, 3]]);
+  });
+});

packages/util/src/array/unzip.ts

@@ -0,0 +1,17 @@
+// Copyright 2017-2022 @polkadot/util authors & contributors
+// SPDX-License-Identifier: Apache-2.0
+
+/**
+ * @name arrayUnzip
+ * @description Splits a single [K, V][] into [K[], V[]]
+ */
+export function arrayUnzip <K, V> (entries: readonly [K, V][]): [K[], V[]] {
+  const keys = new Array<K>(entries.length);
+  const values = new Array<V>(entries.length);
+
+  for (let i = 0; i < entries.length; i++) {
+    [keys[i], values[i]] = entries[i];
+  }
+
+  return [keys, values];
+}

packages/x-fetch/src/node.ts

@@ -12,11 +12,11 @@ export { packageInfo } from './packageInfo';
 const importFetch = import('node-fetch').catch(() => null);
 
 // keep track of the resolved import value
-let resolvedFetch: typeof fetch | null = null;
+let modFn: typeof fetch | null = null;
 
 async function nodeFetch (...args: Parameters<typeof fetch>): Promise<Response> {
-  if (resolvedFetch) {
-    return resolvedFetch(...args);
+  if (modFn) {
+    return modFn(...args);
   }
 
   const mod = await importFetch;
@@ -25,9 +25,9 @@ async function nodeFetch (...args: Parameters<typeof fetch>): Promise<Response>
     throw new Error('Unable to import node-fetch in this environment');
   }
 
-  resolvedFetch = mod.default as unknown as typeof fetch;
+  modFn = mod.default as unknown as typeof fetch;
 
-  return resolvedFetch(...args);
+  return modFn(...args);
 }
 
 export const fetch = extractGlobal('fetch', nodeFetch);