Skip to content

How to check if a date refers to a day in the past in JavaScript

New Course Coming Soon:

Get Really Good at Git

Given a JavaScript date, how do you check if it references a day in the past?

I had this problem: I wanted to check if a date referred to a past day, compared to another date.

Just comparing them using getTime() was not enough, as dates could have a different time.

I ended up using this function:

const firstDateIsPastDayComparedToSecond = (firstDate, secondDate) => {
  if (firstDate.setHours(0,0,0,0) - secondDate.setHours(0,0,0,0) >= 0) { //first date is in future, or it is today
    return false

  return true

I use setHours() to make sure we compare 2 dates at the same time (00:00:00).

Here is the same function with the implicit return, less bloated

const firstDateIsPastDayComparedToSecond = (firstDate, secondDate) => firstDate.setHours(0,0,0,0) - secondDate.setHours(0,0,0,0) < 0

And here is how to use it with a simple example, comparing yesterday to today:

const today = new Date()
const yesterday = new Date(today)

yesterday.setDate(yesterday.getDate() - 1)

firstDateIsPastDayComparedToSecond( yesterday, today) //true
firstDateIsPastDayComparedToSecond( today, yesterday) //false
Are you intimidated by Git? Can’t figure out merge vs rebase? Are you afraid of screwing up something any time you have to do something in Git? Do you rely on ChatGPT or random people’s answer on StackOverflow to fix your problems? Your coworkers are tired of explaining Git to you all the time? Git is something we all need to use, but few of us really master it. I created this course to improve your Git (and GitHub) knowledge at a radical level. A course that helps you feel less frustrated with Git. Launching May 21, 2024. Join the waiting list!
→ Get my JavaScript Beginner's Handbook
→ Read my JavaScript Tutorials on The Valley of Code
→ Read my TypeScript Tutorial on The Valley of Code

Here is how can I help you: