How to type a Date object in TypeScript

Typing a Date object in TypeScript #

Use the Date type to type a Date object in TypeScript, e.g. const date: Date = new Date(). The Date() constructor returns an object that has a type of Date. The interface defines typings for all of the built-in methods on the Date object.

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// 👇️ const date: Date
const date: Date = new Date();

The Date() constructor returns an object that has a type of Date.

If you are using an inline assignment, like in the example, you can let TypeScript infer its type.

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// 👇️ const date: Date
const date = new Date();

You would type a Date object in the same way when using an interface or a type alias.

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interface Delivery {
  shippingDate: Date;
}

const shippingDate = new Date('2023-09-24');

const obj: Delivery = {
  shippingDate,
};

The shippingDate property on the Delivery interface has a type of Date.

If you hover over the Date() constructor, you can see that it returns an object of type Date when instantiated with the new operator.

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interface DateConstructor {
    new(): Date;
    new(value: number | string): Date;
    new(year: number, month: number, date?: number, hours?: number, minutes?: number, seconds?: number, ms?: number): Date;
}

The Date() constructor can be called without any parameters (to get the current date), it could be called with a number or string, or with multiple, comma-separated numbers for the year, month, date, etc.

A good way to check the type of something in TypeScript is to assign is to a variable and hover over the variable.

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const date = new Date();

When using inline assignment, TypeScript is able to infer the type of the value on the right-hand side.

The Date type is defined as an interface and contains typings for all of the date-related built-in methods.

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const date = new Date('2023-09-24');

console.log(date.getFullYear()); // 👉️ 2023

console.log(date.getMonth()); // 👉️ 8

console.log(date.getDate()); // 👉️ 24