Javascript Multiple Choice Questions and Answers Loops in JavaScript

(1) What will be the output of the following JavaScript code?

function printArray(a)
{
    var len = a.length, i = 0;
     if (len == 0)
        console.log("Empty Array");
     else
     {
         do
         {
             console.log(a[i]);
        } while (++i < len);
     }
}

[A] Prints the numbers in the array in order

[B] Prints the numbers in the array in the reverse order

[C] Prints 0 to the length of the array

[D] Prints “Empty Array”

Answer: Prints the numbers in the array in order

(2) What are the three important manipulations done in a for loop on a loop variable?

[A] Updation, Incrementation, Initialization

[B] Initialization,Testing, Updation

[C] Testing, Updation, Testing

[D] Initialization,Testing, Incrementation

Answer: Initialization,Testing, Updation

(3) What will the following JavaScript code snippet work? If not, what will be the error?

function tail(o)
{
    for (; o.next; o = o.next) ;
    return o;
}

[A] No, this will throw an exception as only numerics can be used in a for loop

[B] No, this will not iterate

[C] Yes, this will work

[D] No, this will result in a runtime error with the message “Cannot use Linked List”

Answer: Yes, this will work

(4) What will be the equivalent code of the following JavaScript code?

for(var p in o)
   	console.log(o[p]);

[A]

for (var i = 0;i < a.length;i++)
         console.log(a[i]);

[B]

for (int i = 0;i < a.length;i++)
         console.log(a[i]);

[C]

for (var i = 0;i <= a.length;i++)
     	console.log(a[i]);

[D]

for (var i = 1;i < a.length;i++)
     	console.log(a[i]);

Answer:

for (var i = 0;i < a.length;i++)
    	console.log(a[i]);

(5) One of the special features of an interpreter in reference with the for loop is that ___________

[A] Before each iteration, the interpreter evaluates the variable expression and assigns the name of the property

[B] The iterations can be infinite when an interpreter is used

[C] The body of the loop is executed only once

[D] the iteration is finite when an interpreter is used

Answer: Before each iteration, the interpreter evaluates the variable expression and assigns the name of the property

(6) What will happen if the body of a for/in loop deletes a property that has not yet been enumerated?

[A] The property will be stored in a cache

[B] The loop will not run

[C] That property will not be enumerated

[D] The property will be enumerated

Answer: That property will not be enumerated

(7) What will be the step of the interpreter in a jump statement when an exception is thrown?

[A] The interpreter stops its work

[B] The interpreter throws another exception

[C] The interpreter jumps to the nearest enclosing exception handler

[D] The interpreter throws an error

Answer: The interpreter jumps to the nearest enclosing exception handler

(8) What will be the role of the continue keyword in the following JavaScript code snippet?

while (a != 0)
{
  if (a == 1)
       continue;
   	else
      	 a++;
}

[A] The continue keyword restarts the loop

[B] The continue keyword skips the next iteration

[C] The continue keyword skips the rest of the statements in that iteration

[D] The continue keyword breaks out of the loop

Answer: The continue keyword skips the rest of the statements in that iteration

(9) What could be the task of the statement debugger in the following JavaScript code?

function f(o)
{
     if (o === undefined) debugger;
}

[A] It does nothing but a simple breakpoint

[B] It debugs the error in that statement and restarts the statement's execution

[C] It is used as a keyword that debugs the entire program at once

[D] It is used to find error in the statement

Answer: It does nothing but a simple breakpoint

(10) Among the keywords below, which one is not a statement?

[A] debugger

[B] with

[C] if

[D] use strict

Answer: use strict

(11) What will be the output of the following JavaScript code?

function range(int length)

{

int a=5;

for(int i=0;i< length;i++)

{

console.log(a);

}

range(3);

[A] 5

[B] 555

[C] 3

[D] error

Answer: 555

(12) What will be the output of the following JavaScript code?

var a = 10;

do {

a += 1;

console.log(a);

} while (a < 5);

[A] 11121314

[B] 1112

[C] 12345

[D] 11

Answer: 11

(13) What will be the output of the following JavaScript code?

var a= 0;

var b = 0;

while (a < 3)

{

a++;

b += a;

console.log(b);

}

[A] 135

[B] 123

[C] 013

[D] 01

Answer: 135

(14) What will be the output of the following JavaScript code?

int size=5;

int a=5;

int size=4;

for(int j=size;j>=0;j--)

{

console.log(a);

a=a-2;

}

[A] 5555

[B] 5321

[C] 531-1

[D] 531

Answer: 531-1

(15) What will be the output of the following JavaScript code?

int a=0;

for(a;a<5;a++);

console.log(a);

[A] 0

[B] error

[C] 4

[D] 5

Answer: 5

JavaScript Questions & Answers – Loops in JavaScript | JavaScript MCQs

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