t-comm/lib/validate/is-index.js

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'use strict';

Object.defineProperty(exports, '__esModule', { value: true });

var _typeof = require('@babel/runtime/helpers/typeof');

function _interopDefaultLegacy (e) { return e && typeof e === 'object' && 'default' in e ? e : { 'default': e }; }

var _typeof__default = /*#__PURE__*/_interopDefaultLegacy(_typeof);

/**
 * Used as references for various `Number` constants.
 * @private
 */
var MAX_SAFE_INTEGER = 9007199254740991;
/**
 *  Used to detect unsigned integer values.
 * @private
 */
var reIsUint = /^(?:0|[1-9]\d*)$/;
/**
 * Checks if `value` is a valid array-like index.
 *
 * @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`.
 * @example
 * ```ts
 * isIndex(0); // true
 * isIndex(1); // true
 * isIndex(100); // true
 * isIndex('0'); // true
 * isIndex('999'); // true
 * isIndex(-1); // false
 * isIndex(1.5); // false
 * isIndex('abc'); // false
 * isIndex('01'); // false  // 前导 0
 * isIndex(5, 5); // false  // value 必须 < length
 * isIndex(4, 5); // true
 * isIndex(0, 0); // false  // length 为 0
 * isIndex(Symbol('test')); // false
 * isIndex(null); // false
 * isIndex(undefined); // false
 * ```
 */
function isIndex(value) {
  var length = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : MAX_SAFE_INTEGER;
  var type = _typeof__default["default"](value);
  return !!length && (type == 'number' || type != 'symbol' && reIsUint.test(value)) && value > -1 && value % 1 == 0 && value < length;
}

exports.isIndex = isIndex;