exercises.md

Unit 4 Problem Set #2

Coding Challenge

1. Create a function, makeCounter, that takes a parameter, startingValue and returns a function. When called, the returned function should increment startingValue and then log the number.

   const countFromFive = makeCounter(5);
   countFromFive(); // 6
   countFromFive(); // 7 
   countFromFive(); // 9 
   
   const countFromOneHundred = makeCounter(100);
   countFromOneHundred(); // 101
   countFromOneHundred(); // 102
   countFromOneHundred(); // 103

2. Create a function called , makeFriendList, that returns an object that mutates a private array. The object should have three methods - addFriend, removeFriend, displayFriends.

• addFriend takes a string argument and adds that arguments the private array of friends. addFriend should return "<<friend>> successfully added.".
• removeFriend should take a name and remove that name from the private friend array. If found, it should return "<<friend>> successfully removed.". If not found, it should return "<<friend>> not found.".
• Lastly, displayFriends should return the private friends array.

3. Create a constructor function, Teacher. Objects created with the Teacher function should have the following properties:

• name
• school
• grade
• subject
• students (students should be initialized with the value of an empty array)

Teacher objects should have the following two methods added to their prototype:

• addStudent, which takes a string student argument and adds it to the Teacher object's students property. This method should return the total number of students in the students array.
• changeSchools, which takes a string school argument and reassigns the object's schoolproperty to the passed argument. This method should return the name of the new school.

  const maya = new Teacher('Maya Bhattacharjee', 'The Marcy Lab School', 'post-secondary', 'L&D');
  maya.name;                // 'Maya Bhattacharjee'
  maya.school;              // 'The Marcy Lab School'
  maya.grade;               // 'post-secondary'
  maya.subject;             // 'L&D'
  maya.students;            // []
  
  maya.addStudent('Paul');  // 1
  maya.addStudent('Peter'); // 2
  maya.students;            // ['Paul', 'Peter']
  
  maya.changeSchools('Uncommon Schools'); // 'Uncommon Schools'
  maya.school;              // 'Uncommon Schools'

4. Create a Quadrilateral constructor function. It should be initialized with four arguments that represent the four sides of the quadrilateral. It should have one prototype method: getPerimeter, which returns the perimeter of the quadrilateral.

   const quad = new Quadrilateral(3, 5, 9, 4);
   quad.side1;          // 3
   quad.side2;          // 5
   quad.side3;          // 9
   quad.side4;          // 4
   
   quad.getPerimeter(); // 21

5. A rectangle is a special type of quadrilateral. Rectangles have four 90 degree angles and, thus, have two pairs of congruent sides. Create a Rectangle constructor with an is-a/inheritance relationship with your Quadrilateral constructor. Rectangles should be initialized with two arguments, as rectangles can be described by their length and width. In addition to an inherited getPerimeter method, Rectangles should have a getArea method, that returns the area of the Rectangle object.

   const rect = new Rectangle(30, 40);
   rect.side1;          // 30
   rect.side2;          // 40
   rect.side3;          // 30
   rect.side4;          // 40
   
   rect.getPerimeter(); // 140
   rect.getArea();      // 1200