# 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.

## Examples of the Number.isInteger() Method​

Below are examples of the Number.isInteger() method.

### Is 578 an integer?​

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

Try Editing It

### Is 0.99 an integer?​

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

Try Editing It

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### Is "test" an integer?​

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

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### Is negative 300 an integer?​

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

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### Is zero an integer?​

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

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### 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.