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Javascript dates are notoriously tricky, and the getTime() method is no exception. The “date.getTime is not a function” error occurs when the getTime () method is called on an invalid date. This usually happens when the date is not a valid JavaScript Date object.

Here is an example of how the error occurs –

const date = Date.now();

console.log(date.getTime()); // Uncaught TypeError: date.getTime is not a function

In this example, we called the Date.now() method which returns the current timestamp in milliseconds. We then tried to call the getTime() method on this timestamp which caused the error.

getTime() Method In JavaScript

The getTime () method is used to get the Unix timestamp for a given date – that is, the number of milliseconds since January 1, 1970 UTC. If the date passed to the getTime() method is not a valid Date object, the getTime () method will return NaN.

So, if you see the “date.getTime is not a function” error, it means that the date you are trying to use the getTime() method on is not a valid JavaScript Date object.

There are a few ways to fix this error:

How To Fix JavaScript “gettime is not a function” Error

1) Use A Valid JavaScript Date Object

If you’re getting the “date.getTime is not a function” error, it’s probably because you’re trying to use the getTime () method on an invalid date. To fix this, make sure you’re using a valid JavaScript Date object. For example:

const date = Date.now();

console.log(date.getTime()); //returns an error

Here’s the code that works –

const date = new Date();

console.log(date.getTime()); // 1569438384981

You can also specify a String argument in the new Date() constructor –

const date = new Date("December 17, 1995 03:24:00");

console.log(date.getTime()); // 819199040000

If you use an invalid argument inside the Date() constructor, you will get a NaN result –

const date = new Date("Invalid date");

console.log(date.getTime()); // NaN

2) Use A Valid Timestamp

Another way to fix this error is to use a valid timestamp instead of a date string. For example:

const date = "2019-09-25";

console.log(date.getTime()); // Uncaught TypeError: date.getTime is not a function

Here’s the code that works –

const date = "2019-09-25";

const timestamp = new Date(date).getTime();

console.log(timestamp); // 1569438384981

3) Use A Library Like Moment.js

If you want more flexibility with dates and times, you can use a library like moment.js. moment.js is a lightweight JavaScript library that makes working with dates and times easy.

Here’s how you would use moment.js to fix the “date.getTime is not a function” error –

const date = moment("2019-09-25");

console.log(date.valueOf()); // 1569438384981

Moment.js is available on npm –

npm install moment –save

And you can use it in your project like this:

const moment = require("moment");

You can also use a CDN like this:

<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.24.0/moment.min.js"></script>

4) Use A Number Instead Of A Date

If you need to use the getTime () method on a timestamp that is not a valid JavaScript Date object, you can convert it to a Number first. For example:

const date = Date.now();

console.log(date.getTime()); // Uncaught TypeError: date.getTime is not a function

Here’s the code that works –

const date = Date.now();

const timestamp = Number(date);

console.log(timestamp); // 1569438384981

5) Use A String Instead Of A Date

If you need to use the getTime () method on a timestamp that is not a valid JavaScript Date object, you can convert it to a String first. For example:

const date = Date.now();

console.log(date.getTime()); // Uncaught TypeError: date.getTime is not a function

Here’s the code that works –

const date = Date.now();

const timestamp = String(date);

console.log(timestamp); // "1569438384981"

How To Check If Value Is A Date Object

If you’re not sure whether the value you have is a valid JavaScript Date object, you can use the Object.prototype.toString.call() method to check.

For example:

const date = new Date();

console.log(Object.prototype.toString.call(date)); // "[object Date]"

You can also use typeof to check if a value is a Date object –

const date = new Date();

console.log(typeof date); // "object"

But be aware that typeof will also return “object” for other values like arrays and null. So it’s not a reliable way to check if a value is a Date object.

Conclusion – JavaScript date.getTime is not A Function Error

In this article, you’ve seen five ways to fix the “date.getTime is not a function” error in JavaScript.

Here’s a summary of the techniques you’ve learned:

1) Use a valid JavaScript Date object

2) Use a valid timestamp

3) Use a library like moment.js

4) Use a Number instead of a Date

5) Use a String instead of a Date.

I hope this has been helpful. Happy coding!