index.js

/**
 * lodash 3.1.1 (Custom Build) <https://lodash.com/>
 * Build: `lodash modern modularize exports="npm" -o ./`
 * Copyright 2012-2015 The Dojo Foundation <http://dojofoundation.org/>
 * Based on Underscore.js 1.8.3 <http://underscorejs.org/LICENSE>
 * Copyright 2009-2015 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
 * Available under MIT license <https://lodash.com/license>
 */
var getNative = require('lodash._getnative'),
    isArguments = require('lodash.isarguments'),
    isArray = require('lodash.isarray');

/** Used to detect unsigned integer values. */
var reIsUint = /^\d+$/;

/** Used for native method references. */
var objectProto = Object.prototype;

/** Used to check objects for own properties. */
var hasOwnProperty = objectProto.hasOwnProperty;

/* Native method references for those with the same name as other `lodash` methods. */
var nativeKeys = getNative(Object, 'keys');

/**
 * Used as the [maximum length](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-number.max_safe_integer)
 * of an array-like value.
 */
var MAX_SAFE_INTEGER = 9007199254740991;

/**
 * The base implementation of `_.property` without support for deep paths.
 *
 * @private
 * @param {string} key The key of the property to get.
 * @returns {Function} Returns the new function.
 */
function baseProperty(key) {
  return function(object) {
    return object == null ? undefined : object[key];
  };
}

/**
 * Gets the "length" property value of `object`.
 *
 * **Note:** This function is used to avoid a [JIT bug](https://bugs.webkit.org/show_bug.cgi?id=142792)
 * that affects Safari on at least iOS 8.1-8.3 ARM64.
 *
 * @private
 * @param {Object} object The object to query.
 * @returns {*} Returns the "length" value.
 */
var getLength = baseProperty('length');

/**
 * Checks if `value` is array-like.
 *
 * @private
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is array-like, else `false`.
 */
function isArrayLike(value) {
  return value != null && isLength(getLength(value));
}

/**
 * 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`.
 */
function isIndex(value, length) {
  value = (typeof value == 'number' || reIsUint.test(value)) ? +value : -1;
  length = length == null ? MAX_SAFE_INTEGER : length;
  return value > -1 && value % 1 == 0 && value < length;
}

/**
 * Checks if `value` is a valid array-like length.
 *
 * **Note:** This function is based on [`ToLength`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-tolength).
 *
 * @private
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is a valid length, else `false`.
 */
function isLength(value) {
  return typeof value == 'number' && value > -1 && value % 1 == 0 && value <= MAX_SAFE_INTEGER;
}

/**
 * A fallback implementation of `Object.keys` which creates an array of the
 * own enumerable property names of `object`.
 *
 * @private
 * @param {Object} object The object to query.
 * @returns {Array} Returns the array of property names.
 */
function shimKeys(object) {
  var props = keysIn(object),
      propsLength = props.length,
      length = propsLength && object.length;

  var allowIndexes = !!length && isLength(length) &&
    (isArray(object) || isArguments(object));

  var index = -1,
      result = [];

  while (++index < propsLength) {
    var key = props[index];
    if ((allowIndexes && isIndex(key, length)) || hasOwnProperty.call(object, key)) {
      result.push(key);
    }
  }
  return result;
}

/**
 * Checks if `value` is the [language type](https://es5.github.io/#x8) of `Object`.
 * (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
 *
 * @static
 * @memberOf _
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is an object, else `false`.
 * @example
 *
 * _.isObject({});
 * // => true
 *
 * _.isObject([1, 2, 3]);
 * // => true
 *
 * _.isObject(1);
 * // => false
 */
function isObject(value) {
  // Avoid a V8 JIT bug in Chrome 19-20.
  // See https://code.google.com/p/v8/issues/detail?id=2291 for more details.
  var type = typeof value;
  return !!value && (type == 'object' || type == 'function');
}

/**
 * Creates an array of the own enumerable property names of `object`.
 *
 * **Note:** Non-object values are coerced to objects. See the
 * [ES spec](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-object.keys)
 * for more details.
 *
 * @static
 * @memberOf _
 * @category Object
 * @param {Object} object The object to query.
 * @returns {Array} Returns the array of property names.
 * @example
 *
 * function Foo() {
 *   this.a = 1;
 *   this.b = 2;
 * }
 *
 * Foo.prototype.c = 3;
 *
 * _.keys(new Foo);
 * // => ['a', 'b'] (iteration order is not guaranteed)
 *
 * _.keys('hi');
 * // => ['0', '1']
 */
var keys = !nativeKeys ? shimKeys : function(object) {
  var Ctor = object == null ? null : object.constructor;
  if ((typeof Ctor == 'function' && Ctor.prototype === object) ||
      (typeof object != 'function' && isArrayLike(object))) {
    return shimKeys(object);
  }
  return isObject(object) ? nativeKeys(object) : [];
};

/**
 * Creates an array of the own and inherited enumerable property names of `object`.
 *
 * **Note:** Non-object values are coerced to objects.
 *
 * @static
 * @memberOf _
 * @category Object
 * @param {Object} object The object to query.
 * @returns {Array} Returns the array of property names.
 * @example
 *
 * function Foo() {
 *   this.a = 1;
 *   this.b = 2;
 * }
 *
 * Foo.prototype.c = 3;
 *
 * _.keysIn(new Foo);
 * // => ['a', 'b', 'c'] (iteration order is not guaranteed)
 */
function keysIn(object) {
  if (object == null) {
    return [];
  }
  if (!isObject(object)) {
    object = Object(object);
  }
  var length = object.length;
  length = (length && isLength(length) &&
    (isArray(object) || isArguments(object)) && length) || 0;

  var Ctor = object.constructor,
      index = -1,
      isProto = typeof Ctor == 'function' && Ctor.prototype === object,
      result = Array(length),
      skipIndexes = length > 0;

  while (++index < length) {
    result[index] = (index + '');
  }
  for (var key in object) {
    if (!(skipIndexes && isIndex(key, length)) &&
        !(key == 'constructor' && (isProto || !hasOwnProperty.call(object, key)))) {
      result.push(key);
    }
  }
  return result;
}

module.exports = keys;