feat: add _.compact replacement (silvermine#35)

src/index.ts

@@ -29,6 +29,7 @@ export * from './utils/is-null';
 export * from './utils/is-not-null-or-undefined';
 
 export * from './utils/chunk';
+export * from './utils/compact';
 export * from './utils/flatten';
 export * from './utils/pick';
 export * from './utils/pluck';

src/utils/compact.ts

@@ -0,0 +1,13 @@
+type FalseyVals = '' | 0 | false | null | undefined;
+
+function notFalsy<T>(value: T | FalsyVals): value is T {
+   return value !== '' 
+      && value !== 0
+      && value !== false
+      && value !== null
+      && value !== undefined;
+};
+
+export function compact<T>(arr: (T | FalseyVals)[]): T[] {
+   return arr.filter(notFalsey);
+}

tests/utils/compact.test.ts

@@ -0,0 +1,28 @@
+import { expect } from 'chai';
+import { compact } from '../../src';
+
+describe('compact', () => {
+
+   it('compact arrays', () => {
+      const arrA: (string | number | boolean | null | undefined)[] = [
+         'foo',
+         0,
+         '',
+         true,
+         false,
+         null,
+         'hello',
+         undefined,
+         42,
+      ];
+
+      const arrB: (string | number | boolean)[] = compact(arrA);
+
+      expect(arrB).to.eql([
+         'foo',
+         true,
+         'hello',
+         42,
+      ]);
+   });
+});