Internet Technology

Unit Five: XML, DTD, XSTL, XHTML

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JavaScript Operators || Client Side Scripting || OnlineNotesNepal

JavaScript Operators || Client Side Scripting || OnlineNotesNepal

Operators are symbols or keywords that tell the JavaScript engine to perform some sort of actions. For example, the addition (+) symbol is an operator that tells JavaScript engine to add two variables or values, while the equal-to (==), greater-than (>) or less-than (<) symbols are the operators that tells JavaScript engine to compare two variables or values.

Arithmetic Operator

Operator Description Example Result
+ Addition $a + $b Sum of $a and $b
Subtraction $a – $b Difference of $a and $b
* Multiplication $a * $b Product of $a and $b
/ Division $a / $b Quotient of $a and $b
% Modulus $a % $b Remainder of $a divided by $b, and so on.

var x = 10;

var y = 5;
alert(x + y); // 0utputs: 15

alert(x – y); // 0utputs: 5

alert(x * y); // 0utputs: 50

alert(x / y); // 0utputs: 2

alert(x % y); // 0utputs: 2

JavaScript Assignment Operators

The assignment operators are used to assign values to variables.

Operator Description Example

Is The Same As

=

Assign

$a = $b $a = $b
+=

Add and assign

$a += $b $a= $a + $b
-=

Subtract and assign

$a -= $b $a= $a – $b
*=

Multiply and assign

$a *= $b $a= $a * $b
/=

Divide and assign quotient

$a /= $b $a= $a / $b
%=

Divide and assign modulus

$a %= $b $a= $a % $b

var a; // Declaring Variable
a = 20;
alert(a); // Outputs: 20

a = 20;
a += 30;
alert(a); // Outputs: 50

a = 40;

a -= 20;

alert(a); // Outputs: 20

a = 5;
a *= 15;
alert(a); // Outputs: 75

a = 40;
a /= 10;
alert(a); // Outputs: 4

a = 100;
a %= 15;
alert(a); // Outputs: 10

JavaScript String Operators

There are two operators which can also used be for strings.

Operator Description Example Result
+

Concatenation

str1 + str2

Concatenation of str1 and str2

+=

Concatenation assignment

str1 += str2

Appends the str2 to the str1

Example

var str1 = “Hello”;
var str2 = ” World!”;

alert(str1 + str2); // Outputs: Hello World!

str1 += str2;
alert(str1); // Outputs: Hello World!

JavaScript Incrementing and Decrementing

The increment/decrement operators are used to increment/decrement a variable’s value.

Operator

Name

Effect

++a

Pre-increment

Increments a by one, then returns a

a++

Post-increment

Returns a, then increments a by one

–a

Pre-decrement

Decrements a by one, then returns a

a–

Post-decrement

Returns a, then decrements a by one

var a; // Declaring Variable

a = 12;
alert(++a); // Outputs: 13

alert(a); // Outputs: 13

a = 12;
alert(a++); // Outputs: 12

alert(a); // Outputs: 13

a = 12;
alert(–a); // Outputs: 11

alert(a); // Outputs: 11

a = 12;
alert(a–); // Outputs: 12

alert(a); // Outputs: 11

JavaScript Logical Operators

The logical operators are typically used to combine conditional statements.

Operator

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Name

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Example

Result

&&

And

a && b

True if both a and b are true

||

Or

a || b

True if either a or b is true

!

Not

!a

True if a is not true

var year = 2021;

// Leap years are divisible by 400 or by 4 but not 100
if((year % 400 == 0) || ((year % 100 != 0) && (year % 4 == 0))){

alert(year + ” is a leap year.”);

} else{

alert(year + ” is not a leap year.”); }

JavaScript Comparison Operators

The comparison operators are used to compare two values in a Boolean fashion.

Operator

Name

Example

Result

==

Equal

a == b

True if a is equal to b

===

Identical

a === b

True if a is equal to b, and they are of the same type

!=

Not equal

a != b

True if a is not equal to b

!==

Not identical

a !== b

True if a is not equal to b, or they are not of the same type

<

Less than

a<b

True if a is less than b

>

Greater than

a>b

True if a is greater than b

>=

Greater than or equal to

xa>= b

True if a is greater than or equal to b

<=

Less than or equal to

xa<= b

True if a is less than or equal to b

var a = 35; var b = 45; var c = “35”;

alert(a == c); // Outputs: true

alert(a === c); // Outputs: false

alert(a != b); // Outputs: true

alert(a !== c); // Outputs: true

alert(a < c); // Outputs: true

alert(a > b); // Outputs: false

alert(a <= b); // Outputs: true

alert(a >= b); // Outputs: false

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