Javascript Online Test

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Which of the following is not a reserved word in JavaScript?

interface
throws
program
short

Correct Answer : C

Which built-in method sorts the elements of an array?

changeOrder(order)
order()
sort()
None of the above.

Correct Answer : C

In JavaScript, what is a block of statement?

Conditional block
block that combines a number of statements into a single compound statement
both conditional block and a single statement
block that contains a single statement

Correct Answer : B

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);
     }
}
printArray([
    1, 2, 3, 4, 5
]);

Prints the numbers in the array in order
Prints the numbers in the array in the reverse order
Prints 0 to the length of the array
Prints "Empty Array"

Correct Answer : A

Predict the output of the following JavaScript code.

var a="javascript"; 
var x=a.lastIndexOf("a"); 
document.write(x);

3
0
2
Error

Correct Answer : A

Which answer represents the following order of TYPES? Object, String, Boolean, Number

"{ }", "a string", "false", "0"
[ ], 0, "true", "0"
{ }, "0", false, 0
{ }, hello, "false", "0"

Correct Answer : C

Which one of the following keywords is used for defining the function in the JavaScript?

Void
init
main
function

Correct Answer : D

Which property is object oriented?

function
if statement
variable
keyword

Correct Answer : C

Which of the following function of String object causes a string to be displayed in a small font, as if it were in a <small> tag?

link()
small()
sup()
sub()

Correct Answer : B

Which of these is proper a JSON array?

{ "letters" : [ "a", "b", "c"; ] }
{ 'letters' : {"a", "b", "c" } }
{ "letters" : [ a, b, c ] }
{ "letters" : [ "a", "b", "c" ] }

Correct Answer : D

Which of these is a benefit JSON has over XML?

JSON is more forgiving of poor formatting
JSON has less markup requirements and therefore is lighter than XML
JSON can be written poorly and still be parsed
JSON does not need to be stored in a file to be sent remotely

Correct Answer : B

What event do you use to perform something after the page has finished loading?

onfinished
onload
onunload
oncomplete

Correct Answer : B

Which of the algorithmic languages is not lexical scoping standardized in?

Ada
Pascal
Modula2
Html

Correct Answer : D

What keywords are reserved in JSON and cannot be used as keys?

Value
Object
There are none
Key

Correct Answer : C

To know about an object, whether the object is a prototype (or a part of a prototype chain) of another object, the user can use_______

==operator
equals() method
=== operator
isPrototypeOf() method

Correct Answer : D

In JavaScript, what kind of scoping is used?

Literal scoping
Sequential scoping
Segmental scoping
Lexical scoping

Correct Answer : D

The "function" and " var" are known as:

Keywords
Data types
Declaration statements
Prototypes

Correct Answer : C

What will be the function of the following JavaScript code?

var scope = "global scope";
function checkscope() 
{
    var scope = "local scope"; 
    function f() 
    { 
         return scope; 
    }
    return f;
}

Returns value null
Returns exception
Returns the value in scope
Shows an error message

Correct Answer : C

What will be the output of the following code snippet?

let s = "00000001111111";
let l = 0, r = s.length - 1, ans = -1;
while(l <= r) {
   var mid = Math.floor((l + r) / 2);
   if(s[mid] == '1') {
       ans = mid;
       r = mid - 1;
   }
   else {
       l = mid + 1;
   }
}
console.log(ans);

Correct Answer : B

Can be redeclare a variable that is declared with let keyword?

Correct Answer : B

A disadvantage of JSON is that it requires the use of JavaScript.

False, JSON is language independent.
False, JavaScript must be available although it is not necessary to use.
True, though all browsers have JavaScript enabled.
True, though JavaScript is readily available in today's browsers.

Correct Answer : A

What is the purpose of the dynamic scoping?

Variables can be declared outside the scope
Variables must be declared outside the scope
Variables cannot be declared outside the scope
Variable cannot be declared within the function

Correct Answer : A

What happens if the return statement has no related expression?

It will return a undefined value
It will throw a exception
It will return the 0 as the value
It will throw a error

Correct Answer : A

The statement a===b refers to

Both a and b are equal in value, type and reference address
Both a and b are equal in value
Both a and b are equal in value and type
There is no such statement

Correct Answer : C

What happens when we run this code?

function dog() {
   print("I am a dog.");
}
dog.sound = "Bark";

Syntax Error
“I am a dog” gets printed
Reference Error
Nothing happens

Correct Answer : D

What will be the output of the following code snippet?

var a = "hello";
var sum = 0;
for(var i = 0; i < a.length; i++) {
   sum += (a[i] + 'a');
}
console.log(sum);

0haealalaoa
NaN
0
None of the above

Correct Answer : A

Which function is used to serialize an object into a JSON string in Javascript?

stringify()
parse()
convert()
None of the above

Correct Answer : A

Which is the correct syntax to access an object property in JavaScript?

objectName:propertyName
propertyName
objectName["propertyName"]
Both B. and C.

Correct Answer : D

Each tab in the single web browser window is called as ____________

Browsing context
Browser Information
Both Browser Information & Browsing context
Browser Log

Correct Answer : A

What will be the output of the following JavaScript code?

try{
    const cars = {  
        company: 'Honda'
    };  
    
    Object.seal(cars);
    delete cars.company;
    document.write(cars.company);  
}
catch (err){
    document.write(err.message);
}

undefined
Honda
ValueError
TypeError

Correct Answer : B