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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​

NameTypeDescription
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.