Function isIndex

lodash.js:6355–6363

* 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`.

(value, length)

     * @returns {boolean} Returns `true` if `value` is a valid index, else `false`.
     */
    function isIndex(value, length) {
      var type = typeof value;
      length = length == null ? MAX_SAFE_INTEGER : length;

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

    /**
     * Checks if the given arguments are from an iteratee call.