JS Operators

In this tutorial, you will learn how to manipulate or perform the operations on variables and values using the operators in JavaScript.

What are Operators in JavaScript

Operators are known to be symbols or keywords that program the JavaScript engine to perform some sort of action. For instance, the addition (+) symbol is an operator that instructs the JavaScript engine to add two variables or values together, while the equal to (=), greater than (>), or less than (<) symbols are the operators that instruct JavaScript engine to make a comparison between two variables or values, and so on.

The following sections describe the different operators used in JavaScript.
 

JavaScript Arithmetic Operators

Common arithmetical operations such as addition, subtraction, multiplication of values, and variables are performed by the JavaScript arithmetic operators. Here is a complete list of JavaScript's arithmetic operators:

The following example will show you these arithmetic operators in action:

var x = 10;
var y = 4;
alert(x + y); // 0utputs: 14
alert(x - y); // 0utputs: 6
alert(x * y); // 0utputs: 40
alert(x / y); // 0utputs: 2.5
alert(x % y); // 0utputs: 2

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JavaScript Assignment Operators

The assignment operators are used to assign values to variables.

The following example will show you these assignment operators in action:

Example:

var x;    // Declaring Variable
 
x = 10;
alert(x); // Outputs: 10
 
x = 20;
x += 30;
alert(x); // Outputs: 50
 
x = 50;
x -= 20;
alert(x); // Outputs: 30
 
x = 5;
x *= 25;
alert(x); // Outputs: 125
 
x = 50;
x /= 10;
alert(x); // Outputs: 5
 
x = 100;
x %= 15;
alert(x); // Outputs: 10

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JavaScript String Operators

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

The following example will show you these string operators in action:

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

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JavaScript Incrementing and Decrementing Operators

The increment or decrement operators are used to either increment or decrement a variable's value.

The following example will demonstrate how increment and decrement operators work:

var x; // Declaring Variable
 
x = 10;
alert(++x); // Outputs: 11
alert(x);   // Outputs: 11
 
x = 10;
alert(x++); // Outputs: 10
alert(x);   // Outputs: 11
 
x = 10;
alert(--x); // Outputs: 9
alert(x);   // Outputs: 9
 
x = 10;
alert(x--); // Outputs: 10
alert(x);   // Outputs: 9

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JavaScript Logical Operators

The logical operators are typically used to combine conditional statements.

The logical operators are typically used to combine conditional statements.

The following example will show you how these logical operators actually work:

Example:

var year = 2018;
 
// 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.");
}

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You will learn about conditional statements in JavaScript if/else chapter.

JavaScript Comparison Operators

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

The following example will show you these comparison operators in action:

Example:

var x = 25;
var y = 35;
var z = "25";
 
alert(x == z);  // Outputs: true
alert(x === z); // Outputs: false
alert(x != y);  // Outputs: true
alert(x !== z); // Outputs: true
alert(x < y);   // Outputs: true
alert(x > y);   // Outputs: false
alert(x <= y);  // Outputs: true
alert(x >= y);  // Outputs: false

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