The snippet that has to be used to check if a is not equal to null is _________
if(a!=null)
if (!a)
if(a!null)
if(a!==null)
Correct Answer :
D. if(a!==null)
Explanation: A strict comparison (e.g., ===) is only true if the operands are of the same type and the contents match. The more commonly-used abstract comparison (e.g. ==) converts the operands to the same type before making the comparison. The not-equal operator !== compares 0 to null and evaluates to either true or false.
Related Questions
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
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)
Which of the following Attribute is used to include External JS code inside your HTML Document?
src
ext
script
link
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 method or operator used to identify the array is __________
isarrayType()
==
===
typeof
Among the following, which one is a ternary operator?
+
:
^
?:
A conditional expression is also called a _______________
Alternative to if-else
Immediate if
If-then-else statement
Switch statement
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
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
When does the function name become optional in JavaScript?
When the function is defined as a looping statement
When the function is defined as expressions
When the function is predefined
when the function is called
What is a block statement in JavaScript?
conditional block
block that contains a single statement
both conditional block and a single statement
block that combines multiple statements into a single compound statement
What will be the step of the interpreter in a jump statement when an exception is thrown?
The interpreter stops its work
The interpreter throws another exception
The interpreter jumps to the nearest enclosing exception handler
The interpreter throws an error
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
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
What will be the output of the following JavaScript code?
function printprops(o)
{
for(var p in o)
console.log(p + : + o[p] +
);
}
{
for(var p in o)
console.log(p + : + o[p] +
);
}
Prints the contents of each property of o
Returns undefined
Prints only one property
Prints the address of elements
What will be the output of the following JavaScript code?
var values=[one,two,Three];
var ans=values.shift();
document.writeln(ans);
var ans=values.shift();
document.writeln(ans);
one
two
three
error
What will be the output of the following Javascript code?
var arr = [7, 5, 9, 1];
var min = Math.min.apply(null, arr);
document.writeln(min);
var min = Math.min.apply(null, arr);
document.writeln(min);
7
5
1
9
What will be the output of the following JavaScript code?
const obj = {prop: 12};
Object.preventExtensions(obj);
console.log( Object.isExtensible(obj));
Object.preventExtensions(obj);
console.log( Object.isExtensible(obj));
12
false
true
error
What will be the output of the following JavaScript code?
function equalto()
{
int num=10;
if(num===10)
return true;
else
return false;
}
{
int num=10;
if(num===10)
return true;
else
return false;
}
true
false
runtime error
compilation error
What are the three important manipulations done in a for loop on a loop variable?
Updation, Incrementation, Initialization
Initialization,Testing, Updation
Testing, Updation, Testing
Initialization,Testing, Incrementation
The basic purpose of the toLocaleString() is to _________
return a localised object representation
return a parsed string
return a local time in the string format
return a localized string representation of the object
For the below mentioned code snippet:
var o = new Object();
The equivalent statement is:
var o = Object();
var o;
var o= new Object;
Object o=new Object();
Consider the following code snippet :
var string2Num=parseInt(123xyz);
The result for the above code snippet would be :
123
123xyz
Exception
NaN
Consider the following code snippet.
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);
}
}
What does the above code result?
{
var len = a.length, i = 0;
if (len == 0)
console.log(Empty Array);
else
{
do
{
console.log(a[i]);
} while (++i < len);
}
}
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
What will be the output of the following Javascript code?
<script>
var x = 10;
x *= 5;
document.getElementById("demo").innerHTML = x;
</script>
var x = 10;
x *= 5;
document.getElementById("demo").innerHTML = x;
</script>
5
10
50
Error
A linkage of series of prototype objects is called as ________
prototype stack
prototype chain
prototype class
prototypes
What will be the output of the following JavaScript code?
int sum=0;
var arr = [10,15,20,30];
arr.forEach(function myFunction(element)
{
sum= sum+element;
});
document.writeln(sum);
var arr = [10,15,20,30];
arr.forEach(function myFunction(element)
{
sum= sum+element;
});
document.writeln(sum);
70
75
10
error
What will be the firstname and surname of the following JavaScript code?
var book = {
main title: JavaScript,
'sub-title': The Definitive Guide,
for: all audiences,
author: {
firstname: David,
surname: Flanagan
}
};
main title: JavaScript,
'sub-title': The Definitive Guide,
for: all audiences,
author: {
firstname: David,
surname: Flanagan
}
};
properties
property values
property names
objects
What will be the output of the following JavaScript code?
var val1=[1,2,3];
var val2=[6,7,8];
var result=val1.concat(val2);
document.writeln(result);
var val2=[6,7,8];
var result=val1.concat(val2);
document.writeln(result);
1, 2, 3
Error
1, 2, 3, 6, 7, 8
123