Number

`Number.isSafeInteger`

Determines whether the provided value is a number that is a safe integer, meaning it can be exactly represented as a double-precision floating-point number

Syntax

JavaScript

Number.isSafeInteger(testValue)

Parameters

Parameter	Type	Description
testValue	any	The value to be tested

Return Value

true if the value is a safe integer, false otherwise

Examples

Basic Usage

console.log(Number.isSafeInteger(42)); // true
console.log(Number.isSafeInteger(9007199254740991)); // true (MAX_SAFE_INTEGER)

Practical Example

console.log(Number.isSafeInteger(9007199254740992)); // false
console.log(Number.isSafeInteger(3.14)); // false

Advanced Usage

const MAX = Number.MAX_SAFE_INTEGER;
console.log(MAX); // 9007199254740991
console.log(Number.isSafeInteger(MAX)); // true
console.log(Number.isSafeInteger(MAX + 1)); // false

Understanding Number.isSafeInteger

The Number.isSafeInteger method in JavaScript determines whether the provided value is a number that is a safe integer, meaning it can be exactly represented as a double-precision floating-point number. It belongs to the Number object and is one of the most widely used methods for working with number values in modern JavaScript and TypeScript applications.

The method signature is Number.isSafeInteger(testValue). It accepts 1 parameter: testValue. When called, it returns true if the value is a safe integer, false otherwise. Understanding when and how to use isSafeInteger() helps you write more expressive, readable code.

Common use cases for Number.isSafeInteger include data transformation, input validation, API response processing, and building reusable utility functions. It works well alongside related methods like number-isinteger, number-isfinite, enabling you to chain operations together for complex data manipulation pipelines.

Browser support for Number.isSafeInteger is excellent across all modern browsers including Chrome, Firefox, Safari, and Edge. It is also fully supported in Node.js and Deno. For older environments, transpilation with Babel or a polyfill may be needed.