@feugene/mu/src/internal/isIndex.ts

Helpful TS utilities without dependencies

/** Used as references for various `Number` constants. */
import { reIsUint } from '~/core/vars'

/**
 * Checks if `value` is a valid array-like index.
 *
 * @private
 * @param {*} value The value to check.
 * @param {number} [length=MAX_SAFE_INTEGER] The upper bounds of a valid index.
 * @returns {boolean} Returns `true` if `value` is a valid index, else `false`.
 */
export default function isIndex(value: any, length?: Number): boolean {
  const type = typeof value
  length = length == null ? Number.MAX_SAFE_INTEGER : length

  return (
    !!length &&
    (type === 'number' || (type !== 'symbol' && reIsUint.test(value))) &&
    value > -1 &&
    value % 1 === 0 &&
    value < length
  )
}