# JavaScript Operators || Client Side Scripting || OnlineNotesNepal Table of Contents

# JavaScript Operators

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 Name 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 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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