Check if a Date is before Today's date using JavaScript

Check if a Date is before Today's date using JavaScript #

To check if a date is before today's date:

1. Use the Date() constructor to create a new date.
2. Optionally set the time of the date to midnight.
3. Check if the passed in date is less than today's date.

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function isBeforeToday(date) {
  const today = new Date();

  today.setHours(0, 0, 0, 0);

  return date < today;
}

const yesterday = new Date();
yesterday.setDate(yesterday.getDate() - 1);

const tomorrow = new Date();
tomorrow.setDate(tomorrow.getDate() + 1);

console.log(isBeforeToday(yesterday)); // 👉️ true
console.log(isBeforeToday(tomorrow)); // 👉️ false
console.log(isBeforeToday(new Date())); // 👉️ false

We created a reusable function that checks if the passed in date is before today's date.

The first thing we did in the function is use the Date() constructor to get the current date.

The setHours method takes the hours, minutes, seconds and milliseconds as parameters and changes the values for the given Date instance.

If you remove the line that uses the setHours() method, you'd be checking if the Date is in the past and not necessarily yesterday or further removed.

The last step is to return the result of checking if the passed in date is less than today's date.

We are able to compare the dates because under the hood each date stores a timestamp - the number of milliseconds elapsed between the 1st of January 1970 and the given date.

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const date = new Date('2022-09-24');

// 👇️ 1663977600000
console.log(date.getTime());

If the passed in date is less than today's date, then it's in the past.