hoisting.md

Hoisting

1. What will be the output ?

   console.log(typeof foo);
   
   function foo() {
     return "bar";
   }
   var foo = "bar";

   • A: undefined
   • B: string
   • C: function
   
   
   Answer

   Option: C

---

2. What will be the output ?

   function foo() {
     return "bar";
   }
   var foo;
   
   console.log(typeof foo);

   • A: undefined
   • B: string
   • C: function
   
   
   Answer

   Option: C

---

3. What will be the output ?

   if (true) {
     function foo() {
       console.log(1);
     }
   } else {
     function foo() {
       console.log(2);
     }
   }
   
   foo();

   • A: 1
   • B: 2
   
   
   Answer

   Option: A

---

4. What will be the output ?

   function foo() {
     bar();
   
     return;
   
     function bar() {
       console.log("bar");
     }
   }
   
   foo();

   • A: undefined
   • B: bar
   • C: Uncaught ReferenceError: bar is not defined
   
   
   Answer

   Option: B

---

5. What will be the output ?

   function foo(x) {
     x();
   
     function x() {
       console.log("foo");
     }
   }
   
   foo(function() {
     console.log("bar")
   });

   • A: foo
   • B: bar
   • C: Uncaught ReferenceError: x is not defined
   
   
   Answer

   Option: A

---

6. What will be the output ?

   foo();
   
   function foo() {
     console.log(1);
   }
   
   var foo = function() {
     console.log(2);
   };
   
   function foo() {
     console.log(3);
   }
   
   foo();

   • A: 3 3
   • B: 3 2
   • C: 1 2
   • D: 1 3
   
   
   Answer

   Option: B

---

7. What will be the output ?

   function animal(){
     console.log("Cat");
   }
   
   var otherAnimal;
   
   animal();
   otherAnimal();
   
   otherAnimal = function() {
     console.log("Dog");
   }

   • A: Cat Dog
   • B: Cat undefined
   • C: Cat TypeError: otherAnimal is not a function

   ---

   Answer

   Option: C

8. What are the logged values of a and b ?

   b = function a(){};
   var a = b = 6;
   a = function b(){};
   function b() {};
   function a() {};
   console.log(a,b);

   • A: ƒ b(){} 6
   • B: ƒ a(){} 6
   • C: ƒ b(){} ƒ a(){}
   • D: ƒ a(){} ƒ b(){}
   • E: 6 ƒ a(){}
   • F: 6 ƒ b(){}
   
   
   Answer

   Option: A

9. What are the logged values of a and b ?

   var a = 10;
   console.log("line number 2", a);
   
   function fn() {
     console.log("line number 4", a);
     var a = 20;
     a++;
     console.log("line number 7", a);
     if (a) {
       var a = 30;
       a++;
       console.log("line number 11", a);
     }
     console.log("line number 13", a);
   }
   fn();
   console.log("line number 2", a);

   • A:

   line number 2 10
   line number 4 10
   line number 7 21
   line number 7 31
   line number 13 31
   line number 2 31

   • B:

   line number 2 10
   line number 4 undefined
   line number 7 21
   line number 11 31
   line number 13 31
   line number 2 10

   • C:

   line number 2 10
   line number 4 10
   line number 7 21
   line number 11 31
   line number 13 31
   line number 2 10

   
   
   Answer

   Option: B

---

10. What will be the output?

    function foo() {
      let a = b = 0;
      a++;
      return a;
    }
    
    foo();
    console.log(typeof a);
    console.log(typeof b);

    • A: number \n number
    • B: undefined \n number
    • C: undefined \n undefined
    • D: number \n undefined
    
    
    Answer

    Option: B