# Number.isInteger() – How to Check If a Number Is an Integer

Number.isInteger() checks if its argument is an integer. If so, it returns `true`. Otherwise, the method returns `false`.

## Syntax of the `Number.isInteger()` Method​

`Number.isInteger()` accepts only one required argument. Here is the syntax:

``Number.isInteger(value);``

The `value` argument represents the item you wish to test if it is an integer.

note
• Integers are numbers without decimals. In other words, an integer can be negative, zero, or positive numbers. However, they do not include fractions (decimals).
• Some decimal numbers suffer from loss of precision in JavaScript. Therefore, `Number.isInteger()` will return `true` for numbers like `5.0000000000000001` and `4500000000000000.1`.

## Example 1: Is `578` an Integer?​

``Number.isInteger(578);// The invocation above will return: true``

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## Example 2: Is `0.99` an Integer?​

``Number.isInteger(0.99);// The invocation above will return: false``

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## Example 3: Is `"test"` an Integer?​

``Number.isInteger("test");// The invocation above will return: false``

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## Example 4: Is Negative `300` an Integer?​

``Number.isInteger(-300);// The invocation above will return: true``

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## Example 5: Is Zero an Integer?​

``Number.isInteger(0);// The invocation above will return: true``

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## Example 6: Is `Math.PI` an Integer?​

``Number.isInteger(Math.PI);// The invocation above will return: false``

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## Overview​

This article discussed what `Number.isInteger()` is. We also used examples to see how it works.