Answer by Jordan Szymczyk for Detecting an "invalid date" Date instance in JavaScript

NaN is falsy.invalidDateObject.valueOf() is NaN.

const d = new Date('foo');if (!d.valueOf()) {  console.error('Not a valid date object');}else {  // act on your validated date object}

Even though valueOf() is functionally equivelant to getTime(), I feel it's more appropriate in this context.