TypeScript - test if variable is date type

In this short article, we would like to show how to check if the variable is date type in TypeScript.

Quick solution:

type inputType = Date | number | string;

const isDate = (value: inputType): boolean => {
  return value instanceof Date;
};


// Usage example:

const value1: string = '2020-07-02';
const value2: Date = new Date();
const value3: number = Date.now();

console.log(isDate(value1)); // false
console.log(isDate(value2)); // true
console.log(isDate(value3)); // false

Output:

false
true
false