JavaScript How to Convert Date to Timestamp Easily

To convert a date to a timestamp in JavaScript, use date.getTime() or Date.parse(dateString) which returns the number of milliseconds since January 1, 1970.

Examples

Inputnew Date('2024-06-01T00:00:00Z')

Output1716998400000

Inputnew Date('December 17, 1995 03:24:00')

Output819170640000

InputDate.parse('2024-06-01T00:00:00Z')

Output1716998400000

How to Think About It

To convert a date to a timestamp, think of the date as a point in time. JavaScript stores time as milliseconds from a fixed start date (January 1, 1970). You get this number by calling getTime() on a Date object or by parsing a date string with Date.parse().

Algorithm

1

Create or get a Date object representing the date you want.

2

Call the <code>getTime()</code> method on the Date object to get the timestamp in milliseconds.

3

Alternatively, use <code>Date.parse()</code> with a date string to get the timestamp directly.

4

Return the timestamp value.

Code

javascript

const date = new Date('2024-06-01T00:00:00Z');
const timestamp = date.getTime();
console.log(timestamp);

Output

1716998400000

Dry Run

Let's trace converting '2024-06-01T00:00:00Z' to timestamp using getTime()

1

Create Date object

date = new Date('2024-06-01T00:00:00Z') // represents June 1, 2024 at midnight UTC

2

Get timestamp

timestamp = date.getTime() // returns 1716998400000 milliseconds

3

Output timestamp

console.log(timestamp) // prints 1716998400000

Step	Action	Value
1	Create Date object	2024-06-01T00:00:00.000Z
2	Call getTime()	1716998400000
3	Print timestamp	1716998400000

Why This Works

Step 1: Date object stores time

A JavaScript Date object holds a specific moment in time internally as milliseconds from January 1, 1970.

Step 2: getTime() returns milliseconds

Calling getTime() on a Date object returns this internal millisecond count, which is the timestamp.

Step 3: Date.parse() parses strings

Date.parse() converts a date string directly into the same millisecond timestamp number.

Alternative Approaches

Using Date.now() for current timestamp

javascript

const timestampNow = Date.now();
console.log(timestampNow);

This gets the current timestamp without creating a Date object, but can't convert arbitrary dates.

Using unary plus operator on Date object

javascript

const date = new Date('2024-06-01T00:00:00Z');
const timestamp = +date;
console.log(timestamp);

The unary plus converts the Date object to its timestamp number, a shorter syntax but less explicit.

Complexity: O(1) time, O(1) space

Time Complexity

Getting a timestamp from a Date object is a direct operation with no loops, so it runs in constant time O(1).

Space Complexity

No extra memory is needed beyond the Date object and a number variable, so space complexity is O(1).

Which Approach is Fastest?

getTime() and unary plus are equally fast; Date.parse() parses strings and may be slightly slower but still O(1).

Approach	Time	Space	Best For
date.getTime()	O(1)	O(1)	Converting Date objects to timestamp
Date.parse()	O(1)	O(1)	Converting date strings to timestamp
Unary plus (+date)	O(1)	O(1)	Short syntax for Date to timestamp
Date.now()	O(1)	O(1)	Getting current timestamp only