# JavaScript Compare Two Dates with Date Object Methods

> Compare two JavaScript dates using comparison operators, getTime for equality checks, and Date instance methods, with notes on reference vs value comparison

**URL:** https://sentry.io/answers/how-to-compare-two-dates-with-javascript/

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## The Problem

You want to compare two dates with JavaScript. How can you do this?

## The Solution

To compare two dates, first make a [`Date`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date) object for each date. The `Date` object is used to represent a single moment in time and has methods for formatting dates and doing time zone conversions.

Next, you can compare the two `Date` objects using comparison operators (`>`, `<`, `=`, and `>=`):

```javascript
const date1 = new Date("December 15, 2022");
const date2 = new Date("December 16, 2022");

if (date1 < date2) {
  console.log("date1 is earlier than date2");
} else if (date1 > date2) {
  console.log("date1 is later than date2");
} else {
  console.log("date1 and date2 are the same");
}
// date1 is earlier than date2
```

Comparing two `Date` objects does not work when you use equality operators (`==`, `!=`, `===`, or `!==`):

```javascript
const date1 = new Date("December 15, 2022");
const date2 = new Date("December 15, 2022");
if (date1 === date2) {
  console.log("date1 and date2 are the same");
} else {
  console.log("date1 and date2 are not the same");
}
// date1 and date2 are not the same
```

Equality operators don't work when comparing two `Date` objects, because JavaScript objects are compared by reference, not value. Two `Date` variables are not considered to be the same unless they point to the same `Date` object in memory.

When comparing `Date` objects, it's best to first convert the `Date` to a timestamp number or a date string to avoid any issues with equality operators. If the `Date` constructor is called without the `new` operator, it ignores all arguments and returns a string representing the current time. It's the same as calling `new Date().toString()`.

Use the `toString()` method to return a string representation of the `Date` object showing the date and time in the user's time zone. The `toString()` method is a combination of [`toDateString()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/toDateString) and [`toTimeString()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/toTimeString):

```javascript
console.log(new Date().toString()); // Mon Dec 19 2022 09:51:24 GMT+0200 (South Africa Standard Time)
```

To get a numerical representation of the `Date`, you can call the `getTime()` or `valueOf()` method. Both methods return the number of milliseconds since January 1, 1970, 00:00:00 UTC.

You can also use other `Date` [instance methods](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date#instance_methods) to convert `Date` objects into formatted strings or numbers for comparing. For example, you can get the year, month, week, day, hour, minutes, or seconds of a `Date`:

```javascript
const date = new Date("December 22, 2022, 13:42:33");
const [year, month, week, day, hour, minutes, seconds] = [
  date.getFullYear(),
  date.getMonth(),
  date.getDay(),
  date.getDate(),
  date.getHours(),
  date.getMinutes(),
  date.getSeconds(),
];
console.log(year, month, week, day, hour, minutes, seconds); // 2022 11 4 22 13 42 33
```

The `getMonth()` method returns the index of the month, which starts at 0. The `getDay()` method returns the index of the week, which starts at 0 on Sunday.

For more complex comparisons, you can use a library such as [`date-fns`](https://date-fns.org/), which has multiple utility functions to help make comparisons easier.

## Further Reading

If you're looking to get a deeper understanding of how JavaScript application monitoring works, take a look at the following articles:

- [Understanding the Performance Impact of Generated JavaScript](https://blog.sentry.io/performance-impact-of-generated-javascript/#keep-up-to-date-with-sentrys-javascript-sdk)
- [Making your JavaScript projects less noisy](https://blog.sentry.io/making-your-javascript-projects-less-noisy/#catch-javascript-errors-that-matter)
- [3 Ways to Improve JavaScript Applications](https://blog.sentry.io/3-ways-to-improve-javascript-applications/)
- [JavaScript Debugging Hub](https://sentry.io/answers/javascript/)
- [11 Habits of Highly Effective Developers](https://syntax.fm/show/778/11-habits-of-highly-effective-developers)

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*Source: [sentry.io/answers/how-to-compare-two-dates-with-javascript/](https://sentry.io/answers/how-to-compare-two-dates-with-javascript/)*