Basic Data Structure: FreeCodeCamp

README.md

Basic Data Structure

1. Basic Data Structures: Use an Array to Store a Collection of Data

let yourArray = [1,2,3,true,false,"a","b","C"]; // Change this line

2. Basic Data Structures: Access an Array's Contents Using Bracket Notation

let myArray = ["a", "b", "c", "d"];
// Only change code below this line
myArray[1] = "not b";
// Only change code above this line
console.log(myArray);

3. Basic Data Structures: Add Items to an Array with push() and unshift()

function mixedNumbers(arr) {
  // Only change code below this line
  arr.unshift('I', 2, 'three');
  arr.push(7, 'VIII', 9);
  // Only change code above this line
  return arr;
}

console.log(mixedNumbers(['IV', 5, 'six']));

4. Basic Data Structures: Remove Items from an Array with pop() and shift()

function popShift(arr) {
  let popped = arr.pop(); // Change this line
  let shifted = arr.shift(); // Change this line
  return [shifted, popped];
}

console.log(popShift(['challenge', 'is', 'not', 'complete']));

5. Basic Data Structures: Remove Items Using splice()

const arr = [2, 4, 5, 1, 7, 5, 2, 1];
// Only change code below this line
arr.splice(1,4);
// Only change code above this line
console.log(arr);

6. Basic Data Structures: Add Items Using splice()

function htmlColorNames(arr) {
  // Only change code below this line
  arr.splice(0,2,'DarkSalmon','BlanchedAlmond');
  // Only change code above this line
  return arr;
}

console.log(htmlColorNames(['DarkGoldenRod', 'WhiteSmoke', 'LavenderBlush', 'PaleTurquoise', 'FireBrick']));

7. Basic Data Structures: Copy Array Items Using slice()

function forecast(arr) {
  // Only change code below this line
  arr = arr.slice(2,4);
  return arr;
}

// Only change code above this line
console.log(forecast(['cold', 'rainy', 'warm', 'sunny', 'cool', 'thunderstorms']));

8. Basic Data Structures: Copy an Array with the Spread Operator

function copyMachine(arr, num) {
  let newArr = [];
  while (num >= 1) {
    // Only change code below this line
    newArr.push([...arr]);
    // Only change code above this line
    num--;
  }
  return newArr;
}

console.log(copyMachine([true, false, true], 2));

9. Basic Data Structures: Combine Arrays with the Spread Operator

function spreadOut() {
  let fragment = ['to', 'code'];
  let sentence = ['learning', ...fragment, 'is', 'fun']; // Change this line
  return sentence;
}

console.log(spreadOut());

10. Basic Data Structures: Check For The Presence of an Element With indexOf()

function quickCheck(arr, elem) {
  // Only change code below this line
  return (arr.indexOf(elem) != -1);
  // Only change code above this line
}

console.log(quickCheck(['squash', 'onions', 'shallots'], 'mushrooms'));

11. Basic Data Structures: Iterate Through All an Array's Items Using For Loops

function filteredArray(arr, elem) {
  let newArr = [];
  // Only change code below this line
    for (let i = 0; i < arr.length; i++){
      //Check elem does not exist in arrry
      if (arr[i].indexOf(elem) == -1){
        newArr.push(arr[i]);
      }
    }
  // Only change code above this line
  return newArr;
}

console.log(filteredArray([[3, 2, 3], [1, 6, 3], [3, 13, 26], [19, 3, 9]], 3));

12. Basic Data Structures: Create complex multi-dimensional arrays

let myNestedArray = [
  [
    ['deep'],'unshift', false, 1, 2, 3, 'complex', 'nested',
    [
      ['deeper'],
      [
         ['deepest'],
      ]
    ],
  ],
];

13. Basic Data Structures: Add Key-Value Pairs to JavaScript Objects

let foods = {
  apples: 25,
  oranges: 32,
  plums: 28,
};

// Only change code below this line
foods.bananas = 13;
foods.grapes = 35;
foods.strawberries = 27;
// Only change code above this line

console.log(foods);

14. Basic Data Structures: Modify an Object Nested Within an Object

let userActivity = {
  id: 23894201352,
  date: 'January 1, 2017',
  data: {
    totalUsers: 51,
    online: 42
  }
};

// Only change code below this line
userActivity.data.online = 45;
// Only change code above this line

console.log(userActivity);

15. Basic Data Structures: Access Property Names with Bracket Notation

let foods = {
  apples: 25,
  oranges: 32,
  plums: 28,
  bananas: 13,
  grapes: 35,
  strawberries: 27
};

function checkInventory(scannedItem) {
  // Only change code below this line
  return foods[scannedItem];
  // Only change code above this line
}

console.log(checkInventory("apples"));

16. Basic Data Structures: Use the delete Keyword to Remove Object Properties

let foods = {
  apples: 25,
  oranges: 32,
  plums: 28,
  bananas: 13,
  grapes: 35,
  strawberries: 27
};

// Only change code below this line
delete foods.oranges;
delete foods.plums;
delete foods.strawberries ;

console.log(foods);

17. Basic Data Structures: Check if an Object has a Property

let users = {
  Alan: {
    age: 27,
    online: true
  },
  Jeff: {
    age: 32,
    online: true
  },
  Sarah: {
    age: 48,
    online: true
  },
  Ryan: {
    age: 19,
    online: true
  }
};

function isEveryoneHere(obj) {
  // Only change code below this line
  return obj.hasOwnProperty("Alan") && obj.hasOwnProperty("Jeff") && obj.hasOwnProperty("Sarah") && obj.hasOwnProperty("Ryan")
  // Only change code above this line
}

console.log(isEveryoneHere(users));

18. Basic Data Structures: Iterate Through the Keys of an Object with a for...in Statement

function countOnline(usersObj) {
  // Only change code below this line
  let numOfUser = 0;
  for (let user in usersObj) {
    if(usersObj[user].online){
      numOfUser++;
    }
}
    return numOfUser;
  // Only change code above this line
}

19. Basic Data Structures: Generate an Array of All Object Keys with Object.keys()

let users = {
  Alan: {
    age: 27,
    online: false
  },
  Jeff: {
    age: 32,
    online: true
  },
  Sarah: {
    age: 48,
    online: false
  },
  Ryan: {
    age: 19,
    online: true
  }
};

function getArrayOfUsers(obj) {
  // Only change code below this line
  return Object.keys(obj);
  // Only change code above this line
}

console.log(getArrayOfUsers(users));

20. Basic Data Structures: Modify an Array Stored in an Object

let user = {
  name: 'Kenneth',
  age: 28,
  data: {
    username: 'kennethCodesAllDay',
    joinDate: 'March 26, 2016',
    organization: 'freeCodeCamp',
    friends: [
      'Sam',
      'Kira',
      'Tomo'
    ],
    location: {
      city: 'San Francisco',
      state: 'CA',
      country: 'USA'
    }
  }
};

function addFriend(userObj, friend) {
  // Only change code below this line
  userObj.data.friends.push(friend);
  return userObj.data.friends;
  // Only change code above this line
}

console.log(addFriend(user, 'Pete'));