What will be the output of the following JavaScript code?
var arr=[1,2,3];
var rev=arr.reverse();
document.writeln(rev);
var rev=arr.reverse();
document.writeln(rev);
1, 2, 3
3, 2, 1
3
1
Correct Answer :
B. 3, 2, 1
Explanation: reverse function is a predefined function in array library in Javascript. The function is used to reverse the element of the array. i.e. 3, 2, 1.
Related Questions
The method or operator used to identify the array is __________
isarrayType()
==
===
typeof
What will happen if a return statement does not have an associated expression?
It returns the value 0
It will throw an exception
It returns the undefined value
It will throw an error
When an empty statement is encountered, a JavaScript interpreter __________
Ignores the statement
Prompts to complete the statement
Throws an error
Shows a warning
An expression that can legally appear on the left side of an assignment expression. is a well known explanation for variables, properties of objects, and elements of arrays. They are called ___________
Properties
Prototypes
Lvalue
Definition
JavaScript can be written __________
directly into JS file and included into HTML
directly on the server page
directly into HTML pages
directly into the css file
Consider the following JavaScript statements.
var text = testing: 1, 2, 3; // Sample text
var pattern = /d+/g // Matches all instances of one or more digits
In order to check if the pattern matches with the string text, the statement is ____________
var pattern = /d+/g // Matches all instances of one or more digits
text==pattern
text.equals(pattern)
text.test(pattern)
pattern.test(text)
Consider the following code snippet.
while (a != 0)
{
if (a == 1)
continue;
else
a++;
}
What will be the role of the continue keyword in the above code snippet?
{
if (a == 1)
continue;
else
a++;
}
The continue keyword restarts the loop
The continue keyword skips the next iteration
The continue keyword skips the rest of the statements in that iteration
The continue keyword breaks out of the loop
What will be the output of the following Javascript code?
<script>
document.getElementById("demo").innerHTML = typeof "John"
</script>
document.getElementById("demo").innerHTML = typeof "John"
</script>
integer
number
string
error
The var and function are __________
Keywords
Declaration statements
Data types
Prototypes
The function stops its execution when it encounters?
continue statement
break statement
goto statement
return statement
What will be the output of the following Javascript code?
var txt1 = good;
var txt2 = day;
document.getElementById(demo).innerHTML = txt1 + txt2;
var txt2 = day;
document.getElementById(demo).innerHTML = txt1 + txt2;
good day
goodday
error
undefined
The enumeration order becomes implementation dependent and non-interoperable if ___________
If the object inherits enumerable properties
The object does not have the properties present in the integer array indices
The delete keyword is never used
Object.defineProperty() is not used
What is the observation made in the following JavaScript code?
var count = [1,,3];
The omitted value takes undefined
This results in an error
This results in an exception
The omitted value takes an integer value
What will be the output of the following JavaScript code?
var obj=
{
length:20,
height:35,
}
if (breadth' in obj === false)
{
obj.breadth = 12;
}
console.log(obj.breadth);
{
length:20,
height:35,
}
if (breadth' in obj === false)
{
obj.breadth = 12;
}
console.log(obj.breadth);
20
12
undefined
error
What will be the output of the following JavaScript code?
const object1 = {
property1: 20
};
console.log(Object.is(object1));
property1: 20
};
console.log(Object.is(object1));
20
true
false
error
In the following syntax, the data type within the square brackets must be ___________
book[datatype]=assignment_value;
An integer
A String
An object
Floating point
What will be the output of the following JavaScript code?
function compare()
{
int num=2;
char b=2;
if(a==b)
return true;
else
return false;
}
{
int num=2;
char b=2;
if(a==b)
return true;
else
return false;
}
true
false
runtime error
compilation error
What will be the output of the following JavaScript code?
var a=5 , b=1
var obj = { a : 10 }
with(obj)
{
alert(b)
}
var obj = { a : 10 }
with(obj)
{
alert(b)
}
10
Error
1
5
When an empty statement is encountered, a JavaScript interpreter __________
Ignores the statement
Prompts to complete the statement
Throws an error
Shows a warning
What will be the output of the following JavaScript code?
int a=1;
if(a!=null)
return 1;
else
return 0;
if(a!=null)
return 1;
else
return 0;
1
0
runtime error
compiler error
What will be the output of the following JavaScript code?
var arr=[1,2,3];
var rev=arr.reverse();
document.writeln(rev);
var rev=arr.reverse();
document.writeln(rev);
1, 2, 3
3, 2, 1
3
1
Which keyword is used to define the function in javascript?
void
int
function
main
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);
var result;
switch(grade)
{
case 'A':
result+=10;
case 'B':
result+= 9;
case 'C':
result+= 8;
default:
result+= 0;
}
document.write(result);
10
27
8
0
What happens in the following javaScript code snippet?
var count = 0;
while (count < 10)
{
console.log(count);
count++;
}
while (count < 10)
{
console.log(count);
count++;
}
The values of count are logged or stored in a particular location or storage
The value of count from 0 to 9 is displayed in the console
An error is displayed
An exception is thrown
Which attribute is used to specify that the script is executed when the page has finished parsing? (only for external scripts)
parse
a sync
defer
type
What will be the output of the following JavaScript code?
var arr = [7, 5, 9, 1];
var value = Math.max.apply(null, arr);
document.writeln(value);
var value = Math.max.apply(null, arr);
document.writeln(value);
7
5
1
9
Identify the process done in the following JavaScript code snippet?
o = {x:1, y:{z:[false,null,]}};
s = JSON.stringify(o);
p = JSON.parse(s);
s = JSON.stringify(o);
p = JSON.parse(s);
Object Encapsulation
Object Serialization
Object Abstraction
Object Encoding
Consider the following code snippet
function f(o)
{
if (o === undefined) debugger;
}
What could be the task of the statement debugger?
{
if (o === undefined) debugger;
}
It does nothing but a simple breakpoint
It debugs the error in that statement and restarts the statements execution
It is used as a keyword that debugs the entire program at once
It is used to find error in the statement
Consider the following code snippet :
function constfuncs()
{
var funcs = [];
for(var i = 0; i < 10; i++)
funcs[i] = function() { return i; };
return funcs;
}
var funcs = constfuncs();
funcs[5]()
What does the last statement return ?
{
var funcs = [];
for(var i = 0; i < 10; i++)
funcs[i] = function() { return i; };
return funcs;
}
var funcs = constfuncs();
funcs[5]()
9
0
10
None of the mentioned
The type of a variable that is volatile is _______________
Volatile variable
Mutable variable
Immutable variable
Dynamic variable