TypeError: getFullYear() is not a Function in JavaScript

# TypeError: getFullYear() is not a Function in JavaScript

The "TypeError: getFullYear is not a function" error occurs for multiple reasons:

Not using the new operator when instantiating a Date object.
Calling the getFullYear() method on an object that is not a valid Date.
Misspelling the getFullYear method.
Placing a second set of parentheses when calling the method, e.g. new Date().getFullYear()().

typeerror getfullyear is not a function

Here are some examples of how the error occurs:

index.js

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// ⛔️ did not use `new` operator
const d1 = Date('Sept 24, 22 13:20:18').getFullYear();

// -------------------------------------------------

// ⛔️ did not spell `getFullYear` correctly
const d2 = new Date('Sept 24, 22 13:20:18').getFullyear();

// -------------------------------------------------

// ⛔️ added a second set of parentheses
const d3 = new Date('Sept 24, 22 13:20:18').getFullYear()();

// -------------------------------------------------

// ⛔️ not calling getFullYear on a valid date object
const d4 = {}.getFullYear();

In the first example, we didn't use the new operator to create the Date object, which is what caused the error.

index.js

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// ⛔️ did not use `new` operator
const d1 = Date('Sept 24, 22 13:20:18').getFullYear();

// -----------------------------------------------

// ✅ Correct
const d1 = new Date('Sept 24, 22 13:20:18').getFullYear();
console.log(d1); // 👉️ 2022

use new operator when creating date object

The code for this article is available on GitHub

Make sure to use the new keyword when creating a Date object.

In the second example, we didn't capitalize the getFullYear() method correctly.

index.js

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// ⛔️ did not spell `getFullYear` correctly
const d2 = new Date('Sept 24, 22 13:20:18').getFullyear();

// --------------------------------------------------------

// ✅ correct

const d2 = new Date('Sept 24, 22 13:20:18').getFullYear();
console.log(d2); // 👉️ 2022

capitalize getfullyear method correctly

In the third example, we added an additional set of parentheses, which ended up trying to call the method on an integer.

index.js

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// ⛔️ added a second set of parentheses
const d3 = new Date('Sept 24, 22 13:20:18').getFullYear()();

// --------------------------------------------------------

// ✅ correct

const d3 = new Date('Sept 24, 22 13:20:18').getFullYear();
console.log(d3); // 👉️ 2022

only use one set of parentheses

The code for this article is available on GitHub

The fourth example calls the getFullYear method on an object that isn't a valid Date object.

index.js

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// ⛔️ not calling getFullYear on a valid date object
const d4 = {}.getFullYear();

// --------------------------------------------------------

// ✅ correct

const d4 = new Date().getFullYear();
console.log(d4); // 👉️ 2024

calling getfullyear method on valid date object

Make sure to only call the getFullYear() method on a valid Date object.

The getFullYear method returns the year of the date object the method was called on.

index.js

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const d1 = new Date('Sept 24, 22 13:20:18').getFullYear();
console.log(d1); // 👉️ 2022

getfullyear method returns year of date object

The code for this article is available on GitHub

The getFullYear method can only be called on a valid Date object and returns a four-digit number representing the year.

If you need to get the current year, you don't need to pass anything to the Date() constructor.

index.js

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const current = new Date().getFullYear();
console.log(current); // 👉️ 2024

If you pass an invalid date to the Date() constructor, the getFullYear method will return NaN (not a number).

index.js

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const d1 = new Date('invalid').getFullYear();
console.log(d1); // 👉️ NaN

The code for this article is available on GitHub

You can console.log the value you are calling the getFullYear method on and see if it's a valid Date object.

You should call the getFullYear method on valid Date objects.

# Conclusion

To solve the "getFullYear is not a function" error, make sure to only call the getFullYear() method on a valid Date object.

The getFullYear method returns the year of the date object the method was called on.

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TypeError: getFullYear() is not a Function in JavaScript

# TypeError: getFullYear() is not a Function in JavaScript

# Conclusion

Borislav Hadzhiev