1  /** Used as references for various `Number` constants. */
 2  var MAX_SAFE_INTEGER = 9007199254740991;
 3  
 4  /** Used to detect unsigned integer values. */
 5  var reIsUint = /^(?:0|[1-9]\d*)$/;
 6  
 7  /**
 8   * Checks if `value` is a valid array-like index.
 9   *
10   * @private
11   * @param {*} value The value to check.
12   * @param {number} [length=MAX_SAFE_INTEGER] The upper bounds of a valid index.
13   * @returns {boolean} Returns `true` if `value` is a valid index, else `false`.
14   */
15  function isIndex(value, length) {
16    var type = typeof value;
17    length = length == null ? MAX_SAFE_INTEGER : length;
18  
19    return !!length &&
20      (type == 'number' ||
21        (type != 'symbol' && reIsUint.test(value))) &&
22          (value > -1 && value % 1 == 0 && value < length);
23  }
24  
25  module.exports = isIndex;