What will be the shift() output of the following JavaScript code?
var a = [];
a.unshift(1);
a.unshift(22);
a.shift();
a.unshift(3,[4,5]);
a.shift();
a.shift();
a.shift();
a.unshift(1);
a.unshift(22);
a.shift();
a.unshift(3,[4,5]);
a.shift();
a.shift();
a.shift();
1
[4,5]
[3,4,5]
Exception is thrown
Correct Answer :
A. 1
Explanation: The unshift() and shift() methods behave much like push() and pop(), except that they insert and remove elements from the beginning of an array rather than from the end. unshift() adds an element or elements to the beginning of the array, shifts the existing array elements up to higher indexes to make room, and returns the new length of the array. shift() removes and returns the first element of the array, shifting all subsequent elements down one place to occupy the newly vacant space at the start of the array.
Related Questions
JavaScript Code can be called by using ___________
RMI
Triggering Event
Preprocessor
Function/Method
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
The pop() method of the array does which of the following task?
decrements the total length by 1
increments the total length by 1
prints the first element but no effect on the length
updates the element
What will be the equivalent code of the following JavaScript code?
o.m(x,y);
o.m(x) && o.m(y);
o[m](x,y);
o(m)[x,y];
o.m(x && y);
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?
var grade='A';
var result;
switch(grade)
{
case 'A':
result+=10;
case 'B':
result+= 9;
case 'C':
result+= 8;
default:
result+= 0;
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document.write(result);
var result;
switch(grade)
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result+=10;
case 'B':
result+= 9;
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default:
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document.write(result);
10
27
8
0
What will be the output of the following Javascript code?
var a= 0;
var b = 0;
while (a < 3)
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b += a;
console.log(b);
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var b = 0;
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135
123
013
01
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;
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20
12
undefined
error
What will be the output of the following Javascript code?
<script>
var x = 5;
var y = 2;
var z = x % y;
document.getElementById("demo").innerHTML = z;
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var x = 5;
var y = 2;
var z = x % y;
document.getElementById("demo").innerHTML = z;
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0
1
2
5
What will be the output of the following JavaScript code?
const object1 = {};
a = Symbol('a');
b = Symbol.for('b');
object1[a] = 'harry';
object1[b] = 'derry';
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object1[b] = 'derry';
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0
2
1
Error
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function f(o)
{
if (o === undefined) debugger;
}
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{
if (o === undefined) debugger;
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It does nothing but a simple breakpoint
It debugs the error in that statement and restarts the statements execution
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int sum=0;
var arr = [10,15,20,30];
arr.forEach(function myFunction(element)
{
sum= sum+element;
});
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var arr = [10,15,20,30];
arr.forEach(function myFunction(element)
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70
75
10
error
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[digits][.digits][(E|e)[(+|-)]digits]
[digits][+digits][(E|e)[(+|-)]digits]
[digits][(E|e)[(+|-)]digits]
[.digits][digits][(E|e)[(+|-)]digits]
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The interpreter stops its work
The interpreter throws another exception
The interpreter jumps to the nearest enclosing exception handler
The interpreter throws an error
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o(x,y);
o.m(x) && o.m(y);
m(x,y);
o.m(x,y);
What will be the output of the following JavaScript code?
Int a=1;
if(a>10)
{
document.write(10);
}
else
{
document.write(a);
}
if(a>10)
{
document.write(10);
}
else
{
document.write(a);
}
10
0
1
Undefined
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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
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maps the elements of another array into itself
passes each element of the array and returns the necessary mapped elements
passes each element of the array on which it is invoked to the function you specify, and returns an array containing the values returned by that function
pass the elements of the array into another array
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The property will be stored in a cache
The loop will not run
That property will not be enumerated
The property will be enumerated
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!!(obj1 && obj2);
(obj1 && obj2);
(obj1 && obj2);
Both the lines result in a boolean value True
Both the lines result in a boolean value False
Both the lines checks just for the existence of the object alone
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make all of the own properties of that object non configurable
to configure and bring a writable property
lock down objects into a known state and prevent outside tampering
to include new properties into the object
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void
int
function
main
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Primary Expression
Object Creation Expression
Invocation Expression
Constructor Calling Expression
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directly into JS file and included into HTML
directly on the server page
directly into HTML pages
directly into the css file
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Before each iteration, the interpreter evaluates the variable expression and assigns the name of the property
The iterations can be infinite when an interpreter is used
The body of the loop is executed only once
the iteration is finite when an interpreter is used
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isarrayType()
==
===
typeof
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Syntax error
Missing of semicolons
Division by zero
Missing of Bracket
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var c = counter(), d = counter();
c.count()
d.count()
c.reset()
c.count()
d.count()
The state stored in d is :
c.count()
d.count()
c.reset()
c.count()
d.count()
1
0
Null
Undefined
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if(a!=null)
if (!a)
if(a!null)
if(a!==null)
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Returns the value and continues executing rest of the statements, if any
Returns the value and stops the program
Returns the value and stops executing the function
Stops executing the function and returns the value