js_oop_quiz.md

#Quiz:

1. What’s the result of:

    function A() {}
    A.prototype.name = 'A';
   
    var a = new A();
    var b = new A();
   
    a.name = 'B';
   
    console.log(a.name, b.name);
   

   Answers:

   • 'A', 'A'
   • 'B', 'A'
   • 'B', 'B'

2. What’s the result of:

    function A() {}
    A.prototype = {
        name: 'A';
    };
   
    var a = new A();
   
    A.prototype = {
        name: 'B'
    };
   
    var b = new A();
   
    console.log(a.name, b.name);
   

   Answers:

   • 'A', 'A'
   • 'A', 'B'
   • 'B', 'B'

3. What’s the result of and why:

    var car = {
        color: 'red',
        getColor: function() {
            alert(this.color);
        }
    };
   
    car.getColor();
    var getColor = car.getColor;
    getColor();
   

4. What’s the result of:

    function A() {
        return 5;
    }
   
    var a = new A();
   
    console.log(a);
   

   Answers:

   • 5
   • Object
   • undefined
   • body of function

5. What’s the result of:

    function A() {
        this.name = 'A';
    }
   
    var a = A();
   
    console.log(a.name)
   

   Answers:

   • 'A'
   • TypeError
   • Window
   • depends on browser

6. What’s the result of:

    function A() {}
    A.prototype = 5;
   
    var a = new A()
   
    console.log(Object.getPrototypeOf(a));
   

   Answers:

   • 'object'
   • 5
   • 'undefined'
   • Error