isEven

Determines if a number is even using modulo operation. Checks whether the given number is divisible by 2 with no remainder. Works with both positive and negative integers, and follows mathematical convention that zero is considered even.

Signature

const isEven: (value: number) => boolean

Parameters

Name	Type	Description
value	-	Number to test for evenness

Returns

True if the number is even, false if odd

Examples

Basic even number detection

import { isEven } from '@winglet/common-utils';

console.log(isEven(2)); // true
console.log(isEven(4)); // true
console.log(isEven(0)); // true (zero is even)
console.log(isEven(1)); // false
console.log(isEven(3)); // false

Negative numbers and edge cases

// Negative numbers
console.log(isEven(-2)); // true
console.log(isEven(-4)); // true
console.log(isEven(-1)); // false
console.log(isEven(-3)); // false

// Large numbers
console.log(isEven(1000000)); // true
console.log(isEven(999999)); // false

Playground

import { isEven } from '@winglet/common-utils';

console.log(isEven(2)); // true
console.log(isEven(4)); // true
console.log(isEven(0)); // true (zero is even)
console.log(isEven(1)); // false
console.log(isEven(3)); // false

Notes

Mathematical Properties:

• Zero is considered even (0 = 2 × 0)
• Negative even numbers follow same pattern as positive
• Works with any integer value within JavaScript's safe integer range
• Does not validate input type (assumes numeric input)

Use Cases:

• Array filtering (even indices, even values)
• Alternating patterns in UI (striped tables, zebra patterns)
• Mathematical algorithms requiring parity checks
• Game logic (turn-based systems, alternating players)
• Data validation and categorization
• Optimization algorithms using even/odd properties

Performance: O(1) time and space complexity - single modulo operation.