feat(js-core): add isTruthy()

projects/integration/src/app/api-tests/js-core.spec.ts

@@ -13,6 +13,7 @@ import {
   isPromiseLike,
   isSetEqual,
   isSuperset,
+  isTruthy,
   mapAsKeys,
   mapToObject,
   MigrationManager,
@@ -97,6 +98,10 @@ describe('js-core', () => {
       expect(isSuperset).toBeDefined();
     });
 
+    it('has isTruthy', () => {
+      expect(isTruthy).toBeDefined();
+    });
+
     it('has mapAsKeys', () => {
       expect(mapAsKeys).toBeDefined();
     });

projects/js-core/src/lib/predicates/index.ts

@@ -2,3 +2,4 @@ export { isDefined } from './is-defined';
 export { isEqualAtDepth } from './is-equal-at-depth';
 export { isFalsy } from './is-falsy';
 export { isPromiseLike } from './is-promise-like';
+export { isTruthy } from './is-truthy';

projects/js-core/src/lib/predicates/is-truthy.spec.ts

@@ -0,0 +1,30 @@
+import { isTruthy } from './is-truthy';
+
+describe('isTruthy', () => {
+  // tslint:disable-next-line:only-arrow-functions
+  it('returns `true` for truthy values', function (): void {
+    expect(isTruthy(arguments)).toBe(true);
+    expect(isTruthy([1, 2, 3])).toBe(true);
+    expect(isTruthy(true)).toBe(true);
+    expect(isTruthy(new Date())).toBe(true);
+    expect(isTruthy(new Error())).toBe(true);
+    expect(isTruthy(Array.prototype.slice)).toBe(true);
+    expect(isTruthy({ a: 1 })).toBe(true);
+    expect(isTruthy(1)).toBe(true);
+    expect(isTruthy(/x/)).toBe(true);
+    expect(isTruthy('a')).toBe(true);
+    expect(isTruthy(Symbol('a'))).toBe(true);
+  });
+
+  it('returns `false` for falsy values', () => {
+    expect(isTruthy(false)).toBe(false);
+    expect(isTruthy(0)).toBe(false);
+    expect(isTruthy(-0)).toBe(false);
+    // uncomment when targeting ES2020
+    // expect(isTruthy(0n)).toBe(false);
+    expect(isTruthy('')).toBe(false);
+    expect(isTruthy(null)).toBe(false);
+    expect(isTruthy(undefined)).toBe(false);
+    expect(isTruthy(NaN)).toBe(false);
+  });
+});

projects/js-core/src/lib/predicates/is-truthy.ts

@@ -0,0 +1,6 @@
+/**
+ * Checks if `value` is [truthy](https://developer.mozilla.org/en-US/docs/Glossary/Truthy).
+ */
+export function isTruthy(value: any): boolean {
+  return !!value;
+}