scopes&closures.md

Scopes & Closures

1. Which variables end up being part of func's closure ?

   var c = 10;
   
   function foo(a){
       let b = 8;
       const d = 10;
       return function bar(){
           return a + d + c;
       }
   }
   
   const func = foo(7);

   • A: a and d
   • B: a,b and d
   • C: a,b,c and d
   • D: a,d and c
   
   
   Answer

   Option: A

---

2. What will be the output ?

   const fn = () => {
     a = 2;
     console.log(a);
   }
   
   fn();
   

   • A: undefined
   • B: 2
   • C: Uncaught ReferenceError: a is not defined
   
   
   Answer

   Option: B

---

3. What will be the output ?

   for (var i = 0; i < 4; i++) {
     setTimeout(() => console.log(i), 0)
   }

   • A: 0 1 2 3
   • B: 4 4 4 4
   
   
   Answer

   Option: B

---

4. What will be the output?

   for(let i = 0; i < 5; i++){
       setTimeout(() => console.log(i), 1);
   }

   • A: 0 0 0 0 0
   • B: 1 2 3 4 5
   • C: 5 5 5 5 5
   • D: 0 1 2 3 4
   
   
   Answer

   Option: D

---

5. What will be the output?

   let count = 0;
   (function immediate() {
     if (count === 0) {
       let count = 1;
       console.log(count);
     }
     console.log(count);
   })();

   • A: 0 0
   • B: 1 1
   • C: 1 0
   • D: 0 1
   
   
   Answer

   Option: C

---

6. what would be the typeof a and typeof b

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

   • A: Number Number
   • B: Number undefined
   • C: undefined Number
   • D: not define not define
   
   
   Answer

   Option: C