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JavaScript Questions & Answers – Loops in JavaScript | JavaScript MCQs

Questions
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
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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

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