// Complete the following underscore functions.

// Reference http://underscorejs.org/ for examples.

/* eslint-disable no-unused-vars */

// Object.keys(obj).forEach(key => {

// console.log(key, obj[key]);

// });

const keys = obj => (

// Retrieve all the names of the object's properties.

// Return the keys as strings in an array.

// Based on http://underscorejs.org/#keys

Object.keys(obj)

);

const values = (obj) => {

// Return all of the values of the object's own properties.

// Ignore functions

// http://underscorejs.org/#values

const result = [];

Object.keys(obj).forEach((key) => {

result.push(obj[key]);

});

return result;

};

const mapObject = (obj, cb) => {

// Like map for arrays, but for objects. Transform the value of each property in turn.

// http://underscorejs.org/#mapObject

Object.keys(obj).forEach((key) => {

obj[key] = cb(obj[key]);

});

return obj;

};

const pairs = (obj) => {

// Convert an object into a list (array) of [key, value] pairs.

// http://underscorejs.org/#pairs

const result = [];

Object.keys(obj).forEach((key) => {

result.push([key, obj[key]]);

});

return result;

};

const invert = (obj) => {

// Returns a copy of the object where the keys have become the values and the values the keys.

// Assume that all of the object's values will be unique and string serializable.

// http://underscorejs.org/#invert

const tempObj = {};

Object.keys(obj).forEach((key) => {

tempObj[obj[key]] = key;

});

return tempObj;

};

const defaults = (obj, defaultProps) => {

// Fill in undefined properties that match properties on the `defaultProps` parameter object.

// Return `obj`.

// http://underscorejs.org/#defaults

Object.keys(defaultProps).forEach((key) => {

if (!(key in obj)) obj[key] = defaultProps[key];

});

return obj;

};

/* eslint-enable no-unused-vars */

module.exports = {

keys,

values,

mapObject,

pairs,

invert,

defaults,

};