250+ TOP MCQs on Statements and Answers

var a=5 , b=1
var obj = { a : 10 }
with(obj) 
{
      alert(b)
}

for(var num=10;num>=1;num--)
{
           document.writeln(num);
}

var num=10;
while(num>=1)
{
       document.writeln(num);
       num++;
}

switch(expression)
{
    statements
}

var count = 0;
while (count < 10) 
{
     console.log(count);
     count++;
}

Answer: b
Clarification: Console.log is a predefined function in JavaScript which takes the value as an argument of its function.console.log prints this value in the argument in the console at the time of execution of the code.

10. The enumeration order becomes implementation dependent and non-interoperable if ___________
a) If the object inherits enumerable properties
b) The object does not have the properties present in the integer array indices
c) The delete keyword is never used
d) Object.defineProperty() is not used
Answer: a
Clarification: In computer programming, an enumerated type (also called enumeration or enum) is a data type consisting of a set of named values called elements, members or enumerators of the type. The enumerator names are usually identifiers that behave as constants in the language.

11. What will be the output of the following JavaScript code?

Int a=1;
if(a>10)
{  
    document.write(10);  
} 
else
{
    document.write(a);  
}

a) 10
b) 0
c) 1
d) Undefined
Answer: c
Clarification: The if else statement is a part of the javascript conditioning statements. The line of code inside the “if” statement is executed if the value passed to “if” is 1.

12. What will be the output of the following JavaScript code?

var grade='B';  
var result;  
switch(grade)
{  
    case 'A':
    {  
        result+="10"; 
        break;
    } 
    case 'B':
    {  
        result+=" 9";
        break;
    }  
    case 'C':
    {  
        result+=" 8";
        break;
    }  
    default:  
    result+=" 0";  
}  
document.write(result);

a) 10
b) 9
c) 8
d) 0
Answer: b
Clarification: The above code contains a switch loop. It is used as an alternative to if else statement. One of the given condition is satisfied according to the input of the switch case and the output is decided accordingly.

13. What will be the output of the following JavaScript code?

var grade='A';  
var result;  
switch(grade)
{  
    case 'A':  
        result+="10";  
    case 'B':  
        result+=" 9";  
    case 'C':  
        result+=" 8";  
    default:  
        result+=" 0";  
}  
document.write(result);

a) 10
b) 27
c) 8
d) 0
Answer: b
Clarification: The above code does not have a break statement after the cases in the switch loop. Therefore all of the cases following “A” will get executed.

14. What will be the output of the following JavaScript code?

int a=4;
int b=1;
int c=0;
If(a==b)
    document.write(a);
else if(a==c)
    document.write(a);
else
    document.write(c);

a) 4
b) 1
c) Error
d) 0
Answer: d
Clarification: For checking more than one condition the if else if loop is used. It is the extension of if else loop which is also sometimes known as if else ladder.

15. What will be the output of the following JavaScript code?

var grade='E';  
var result;  
switch(grade)
{  
    case 'A':  
        result+="10";  
    case 'B':  
        result+=" 9";  
    case 'C':  
        result+=" 8";  
    default:  
        result+=" 0";  
}  
document.write(result);

a) 10
b) 0
c) 18
d) 17
Answer: b
Clarification: The switch case contains a default case along with the other cases. The default case gets executed when no other case results into true.