--- /dev/null
+var isArguments = require('../lang/isArguments'),
+ isArray = require('../lang/isArray'),
+ isIndex = require('../internal/isIndex'),
+ isLength = require('../internal/isLength'),
+ isObject = require('../lang/isObject');
+
+/** Used for native method references. */
+var objectProto = Object.prototype;
+
+/** Used to check objects for own properties. */
+var hasOwnProperty = objectProto.hasOwnProperty;
+
+/**
+ * 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 = keysIn;