8_ObjectsChallenges.js

// Week 3 - Objects

// In the following exercises, you will need to place your code or answer underneath each
// exercise prompt.

// First try answering these without using references or looking up any information.
// Then, check your answer by using references and/or running your code.
// You can run your JS code using the Chrome or Firefox Developer tools, or by using Node.js or using Replit.com
// Feel free to update your answers if you got them wrong at first -- this exercise is for your own learning.
// But make sure you understand why the correct answer is right.

// Exercise 1. Write a function called keys, which accepts an object and returns an array of all of the keys in the object.
// IMPORTANT: Do not use the built in Object.keys() function!
// Examples:
// let obj = { a: 1, b: 2, c: 3 };
// keys(obj); // ["a", "b", "c"]
// let obj2 = { first: 'Matt', last: 'Lane' };
// keys(obj2); // ["first", "last"]
// let obj3 = {};
// keys(obj3); // []

function objKeys(obj){
  let newArr = [];
  for (let keys in obj){
    newArr.push(keys);
  }
  return newArr;
};
// Exercise 2. Write a function called values, which accepts an object and returns an array of all of the values in the object.
// IMPORTANT: Do not use the built in Object.values() function!
// Examples:
// let obj = { a: 1, b: 2, c: 3 };
// values(obj); // [1,2,3]
// let obj2 = { first: 'Matt', last: 'Lane', isDogOwner: true };
// values(obj2); // ["Matt", "Lane", true]
// let obj3 = {};
// values(obj3); // []

function objValues (obj){
  let newValuesArr = [];
  for (let keys in obj){
    newValuesArr.push(obj[keys])
  } return newValuesArr
}

// Exercise 3. Write a function called entries, which accepts an object and returns an array of arrays of key-value pairs.
// In other words, each sub-array is an "entry" in the object with two elements: the first element is the key, and the second element is the value.
// IMPORTANT: Do not use the built in Object.entries() function!
// Examples:
// let obj = { a: 1, b: 2, c: 3 };
// entries(obj);
// [["a",1], ["b",2], ["c",3]]
// let obj2 = { first: 'Matt', last: 'Lane', isDogOwner: true };
// entries(obj2);
// [["first","Matt"], ["last","Lane"], ["isDogOwner",true]]
// let obj3 = {};
// entries(obj3); // []

function objEntries(obj){
  let newObjEntries = [];
  for (let keys in obj){
    newObjEntries.push([keys, obj[keys]]);
  } 
  return newObjEntries; 
}

// Exercise 4. Write a function called pluck, which takes an array of objects and the name of a key.
// The function should return an array containing the value associated with that key for each object, or undefined if that key is not present in the object.
// Examples:
// pluck([{ name: "Tim" }, { name: "Matt" }, { name: "Elie" }],'name')
// ["Tim", "Matt", "Elie"]
// pluck([{ name: "Tim", isBoatOwner: true }, { name: "Matt", isBoatOwner: false }, { name: "Elie" }],'isBoatOwner')
// [true, false, undefined]
function pluck (arrOfObjs, str){
  for (let index of arrOfObjs){
    for (let key in index){
      if (key === str){
        return true;
      }
    }
  } return false; 
}

// Exercise 5. Write a function called stringFromObject that generates a string from an object's key/value pairs.
// The format should be "key = value, key = value".
// Each key/value pair should be separated by a comma and space except for the last pair.
// Examples:
// stringFromObject({ a: 1, b: '2' });
// "a = 1, b = 2"
// stringFromObject({ name: 'Elie', job: 'Instructor', isCatOwner: false });
// "name = Elie, job = Instructor, isCatOwner = false"
// stringFromObject({}); // ""
function stringFromObject (obj){
let finalStr = "";
  for (let keys in obj){
    finalStr = finalStr + `${keys} = ${obj[keys]}, `
  } 
  let slice =  finalStr.slice(0, (finalStr.length - 2));
  return `"${slice}"`
}

// Exercise 6. Write a function called minMaxKeyInObject that accepts an object with numeric keys.*
// The function should return an array with the following format: [lowestKey, highestKey]
// Examples:
// minMaxKeyInObject({ 2: 'a', 7: 'b', 1: 'c', 10: 'd', 4: 'e' });
// [1, 10]
// minMaxKeyInObject({ 1: 'Elie', 4: 'Matt', 2: 'Tim' });
// [1, 4]

function minMaxKeyInObject (obj){
  let minKeys = Infinity; 
  let maxKeys = -Infinity;
  let finalArr = [];
  
  for (keys in obj){
    let key = Number(keys);
    if (key < minKeys){
      minKeys = key;
    }
    else if (key > maxKeys){
      maxKeys = key; 
    }
  } finalArr.push(minKeys);
    finalArr.push(maxKeys);
  return finalArr; 
}