Reject invalid dates despite being valid Date objects

Author: przemyslawzalewski

date/valid.js

@@ -1 +1,2 @@
-export default date => (date ? date instanceof Date : false);
+export default date =>
+  date ? date instanceof Date && !Number.isNaN(date.valueOf()) : false;

date/valid.json

@@ -1,6 +1,6 @@
 {
   "name": "valid",
-  "description": "TODO: Fill short description here.",
+  "description": "Checks if the given date is a valid date.",
   "signature": "(date?: any) => boolean",
   "examples": [
     {

date/valid.test.ts

@@ -3,7 +3,18 @@
 import valid from "./valid.ts";
 
 describe("valid", () => {
-  it.skip("TODO", () => {
-    expect(valid()).toBeDefined();
+  it("checks if the given date is a valid date", () => {
+    expect(valid(new Date())).toBe(true);
+    expect(valid(new Date("2020-01-31T09:52:31.618Z"))).toBe(true);
+    expect(valid(new Date("77724e10-2ffa-45cc-b05d-a91a846a6080"))).toBe(false);
+  });
+
+  it("handles missing and falsy values", () => {
+    expect(valid(undefined)).toBe(false);
+    expect(valid(null)).toBe(false);
+    expect(valid(false)).toBe(false);
+    expect(valid(0)).toBe(false);
+    expect(valid(NaN)).toBe(false);
+    expect(valid("")).toBe(false);
   });
 });

date/valid.ts

@@ -1 +1,2 @@
-export default (date?: any): boolean => (date ? date instanceof Date : false);
+export default (date?: any): boolean =>
+  date ? date instanceof Date && !Number.isNaN(date.valueOf()) : false;