Convert a Date to Unix timestamp using JavaScript

Convert a Date to Unix timestamp using JavaScript #

To convert a date to a Unix timestamp:

1. Create a Date object using the Date() constructor.
2. Get a timestamp in milliseconds using the getTime() method.
3. Convert the result to seconds by dividing by 1000.

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const dateStr = '2022-06-22';

const date = new Date(dateStr);
console.log(date); // 👉️ Wed Jun 22 2022

const timestampInMs = date.getTime();

const unixTimestamp = Math.floor(date.getTime() / 1000);
console.log(unixTimestamp); // 👉️ 1655856000

We used the Date() constructor to create a Date object.

If you have a date string, pass it to the Date() constructor to get a Date object.

The getTime method returns the number of milliseconds since the Unix Epoch (1st of January, 1970 00:00:00).

The Math.floor function, rounds a number down if the number has a decimal, otherwise it returns the number as is.

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console.log(Math.floor(2.99)); // 👉️ 2
console.log(Math.floor(2.01)); // 👉️ 2
console.log(Math.floor(2)); // 👉️ 2

This ensures that we don't get a decimal when converting the milliseconds to seconds.

If you have difficulties creating a valid Date object, you can pass 2 types of parameters to the Date() constructor:

1. a valid ISO 8601 string, formatted as YYYY-MM-DDTHH:mm:ss.sssZ, or just YYYY-MM-DD, if you only have a date without time.
2. multiple, comma-separated parameters that represent the year, month (0 = January to 11 = December), day of the month, hours, minutes and seconds.

Here is an example where we have a date and time string that is formatted as MM/DD/YYYY hh:mm:ss (could be any other format) and pass each individual value to the Date() constructor to create a valid Date and get its Unix timestamp.

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// 👇️ Formatted as MM/DD/YYYY hh:mm:ss
const dateStr = '09/24/2022 09:25:32';

const [dateComponents, timeComponents] = dateStr.split(' ');
console.log(dateComponents); // 👉️ "09/24/2022"
console.log(timeComponents); // 👉️ "09:25:32"

const [month, day, year] = dateComponents.split('/');
const [hours, minutes, seconds] = timeComponents.split(':');

const date = new Date(+year, month - 1, +day, +hours, +minutes, +seconds);
console.log(date); // 👉️ Sat Sep 24 2022 09:25:32

// ✅ Get Unix timestamp
const unixTimestamp = Math.floor(date.getTime() / 1000);
console.log(unixTimestamp); // 👉️ 1664000732

The first thing we did was split the date and time string on the space, so we can get the date and time components as separate strings.

We also split the time string on each colon and assigned the hours, minutes and seconds to variables.

Notice that we subtracted 1 from the month when passing it to the Date() constructor.

We passed all of the parameters to the Date() constructor to create a Date object and got the Unix timestamp by calling the getTime() method and dividing the result by 1000.