// Complete the following underscore functions.

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

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

return Object.keys(obj);

};

const values = (obj) => {

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

// Ignore functions

// http://underscorejs.org/#

const objKeys = Object.keys(obj);

const result = [];

objKeys.forEach((k) => {

return result.push(obj[k]);

});

// for (const key in obj) {

// if (Object.prototype.hasOwnProperty.call(obj, 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

const objKeys = Object.keys(obj);

const returnObj = Object.assign({}, obj);

objKeys.forEach((k) => {

returnObj[k] = cb(obj[k]);

});

return returnObj;

};

const pairs = (obj) => {

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

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

const objKeys = Object.keys(obj);

const result = [];

objKeys.forEach((k) => {

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

});

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 objKeys = Object.keys(obj);

const returnObj = {};

objKeys.forEach((k) => {

returnObj[obj[k]] = k;

});

return returnObj;

};

const defaults = (obj, defaultProps) => {

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

// Return `obj`.

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

function hasKey(o, ky) {

// const objKeys = Object.keys(o);

// return objKeys.includes(ky) || o[ky] !== undefined;

return o[ky] === undefined;

}

const defaultKeys = Object.keys(defaultProps);

defaultKeys.forEach((k) => {

if (hasKey(obj, k)) {

obj[k] = defaultProps[k];

}

});

// for (const key in objKeys) {

// if (obj[key] === undefined && defaultProps.hasKey(key)) {

// obj[key] = defaultProps[key];

// }

// }

return obj;

};

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

module.exports = {

keys,

values,

mapObject,

pairs,

invert,

defaults

};