isBetween function

Checks whether a number lies between two bounds.

import { isBetween } from 'utils';

Signature

export function isBetween(value: number, min: number, max: number, isInclusive = true): boolean

Parameters

Name	Description
value	The number to check.
min	The lower bound.
max	The upper bound.
isInclusive	Whether the bounds themselves are between. Defaults to true.

Returns

true when value lies within the bounds.

Example

isBetween(10, 0, 10); // true
isBetween(10, 0, 10, false); // false

Tests

Line coverage: 100 %.

• ✅ checks 5 in [0, 10] inclusively as true
• ✅ checks 0 in [0, 10] inclusively as true
• ✅ checks 10 in [0, 10] inclusively as true
• ✅ checks 11 in [0, 10] inclusively as false
• ✅ excludes the bounds when not inclusive

Source

src/math/is-between.ts (on GitHub)

Source code

/**
 * Checks whether a number lies between two bounds.
 *
 * @param value - The number to check.
 * @param min - The lower bound.
 * @param max - The upper bound.
 * @param isInclusive - Whether the bounds themselves are between. Defaults to `true`.
 * @returns `true` when `value` lies within the bounds.
 * @example
 * isBetween(10, 0, 10); // true
 * isBetween(10, 0, 10, false); // false
 */
export function isBetween(value: number, min: number, max: number, isInclusive = true): boolean {
  return isInclusive ? value >= min && value <= max : value > min && value < max;
}

Test file

import { isBetween } from './is-between';

describe(isBetween, () => {
  it.for([
    [5, 0, 10, true],
    [0, 0, 10, true],
    [10, 0, 10, true],
    [11, 0, 10, false],
  ] as const)('checks %s in [%s, %s] inclusively as %s', ([value, min, max, expected]) => {
    expect(isBetween(value, min, max, true)).toBe(expected);
  });

  it('excludes the bounds when not inclusive', () => {
    expect(isBetween(0, 0, 10, false)).toBe(false);
    expect(isBetween(10, 0, 10, false)).toBe(false);
    expect(isBetween(5, 0, 10, false)).toBe(true);
  });
});

Keywords: is, between, math, function