Compare Dates without Time in JavaScript

Compare Dates without Time in JavaScript #

To compare dates without time:

Create a copy of each date.
Use the setUTCHours() method to set the time on the copied dates to midnight.
Compare the output from calling the getTime() method on the dates.

index.js

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const date1 = new Date('2022-01-23T06:55:31.820Z');
const date2 = new Date('2022-01-23T09:30:24.820Z');

const date1WithoutTime = new Date(date1.getTime());
const date2WithoutTime = new Date(date2.getTime());

date1WithoutTime.setUTCHours(0, 0, 0, 0);
date2WithoutTime.setUTCHours(0, 0, 0, 0);

if (date1WithoutTime.getTime() === date2WithoutTime.getTime()) {
  // ✅ This runs 👇️ (dates are the same)
  console.log('dates are the same');
} else {
  console.log('dates are not the same');
}

if (date1WithoutTime.getTime() > date2WithoutTime.getTime()) {
  console.log('date1 comes after date2');
} else if (date1WithoutTime.getTime() === date2WithoutTime.getTime()) {
  // ✅ This runs 👇️ (dates are the same)
  console.log('date1 and date2 are the same');
} else {
  console.log('date2 comes after date1');
}

We used the Date() constructor to create 2 Date objects that both store the 23rd of January, 2022.

To be able to compare the dates and ignore the time, we have to reset the time of the dates to midnight (or simply the same hour, minutes, seconds and milliseconds).

The setUTCHours method takes the hours, minutes, seconds and milliseconds as parameters and sets the values on the given date according to universal time.

However, the setUTCHours method mutates the Date object in place, which might not be what you want.

This is why we used the getTime method to get a timestamp of the elapsed milliseconds between the 1st of January 1970 00:00:00 and the given date.

We can pass the timestamp to the Date() constructor to create a copy of the Date object.

We used the setUTCHours method to set the time for the dates to midnight, so we can compare the dates ignoring the time.

The getTime method returns a number that represents the milliseconds elapsed between the Unix Epoch and the given date.

index.js

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// 👇️ 1642944933161
console.log(new Date().getTime());

If we have two dates that store the same year, month and day of the month, then the timestamps are going to be equal because we set the time on both dates to midnight.

If one date is greater than another, then its timestamp is going to store a larger number because more time has elapsed between the Unix Epoch and the specific date.

You can compare the output from getTime() just like you would compare numbers in JavaScript.

Here is an example where date1 stores a value for the 23rd of February, 2022 and date2 stores a value for the 27th of April, 2022.

index.js

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const date1 = new Date('2022-02-23T06:55:31.820Z');
const date2 = new Date('2022-04-27T09:30:24.820Z');

const date1WithoutTime = new Date(date1.getTime());
const date2WithoutTime = new Date(date2.getTime());

date1WithoutTime.setUTCHours(0, 0, 0, 0);
date2WithoutTime.setUTCHours(0, 0, 0, 0);

if (date1WithoutTime.getTime() === date2WithoutTime.getTime()) {
  console.log('dates are the same');
} else {
  // ✅ This runs 👇️ (dates are NOT the same)
  console.log('dates are not the same');
}

if (date1WithoutTime.getTime() > date2WithoutTime.getTime()) {
  console.log('date1 comes after date2');
} else if (date1WithoutTime.getTime() === date2WithoutTime.getTime()) {
  console.log('date1 and date2 are the same');
} else {
  // ✅ This runs 👇️ (date2 comes after date1)
  console.log('date2 comes after date1');
}

The value in the date2 variable comes after the one in the date1 variable, therefore its timestamp is a greater number, so the else statement runs in both conditionals.

Compare Dates without Time in JavaScript

Compare Dates without Time in JavaScript #

Borislav Hadzhiev