JS Operators

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What are Operators in JavaScript

Operators are symbols or keywords that instruct the JavaScript engine to carry out certain actions. For example, the addition (+) symbol is an operator that directs the JavaScript engine to sum two variables or values. Similarly, the equal-to (==), greater-than (>), or less-than (<) symbols are operators that instruct the JavaScript engine to compare two variables or values, and so forth.

The following sections explain the different operators used in JavaScript.

JavaScript Arithmetic Operators

Arithmetic operators are utilized to conduct basic mathematical operations like addition, subtraction, multiplication, and more. Below is a complete list of JavaScript's arithmetic operators:

Operator	Description	Example	Result
`+`	Addition	`x + y`	Sum of x and y
`-`	Subtraction	`x - y`	Difference of x and y.
`*`	Multiplication	`x * y`	Product of x and y.
`/`	Division	`x / y`	Quotient of x and y
`%`	Modulus	`x % y`	Remainder of x divided by y

The following example will demonstrate these arithmetic operators in use:

Example

Try this code »

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

JavaScript Assignment Operators

Assignment operators are used to set values to variables.

Operator	Description	Example	Is The Same As
`=`	Assign	`x = y`	`x = y`
`+=`	Add and assign	`x += y`	`x = x + y`
`-=`	Subtract and assign	`x -= y`	`x = x - y`
`*=`	Multiply and assign	`x *= y`	`x = x * y`
`/=`	Divide and assign quotient	`x /= y`	`x = x / y`
`%=`	Divide and assign modulus	`x %= y`	`x = x % y`

The following example will demonstrate these assignment operators in use:

Example

Try this code »

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

JavaScript String Operators

There are two operators that can also be used with strings.

Operator	Description	Example	Result
`+`	Concatenation	`str1 + str2`	Concatenation of str1 and str2
`+=`	Concatenation assignment	`str1 += str2`	Appends the str2 to the str1

The following example will demonstrate these string operators in use:

Example

Try this code »

var str1 = "Hello";
var str2 = " World!";

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

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

JavaScript Incrementing and Decrementing Operators

The increment and decrement operators are used to increase or decrease a variable's value.

Operator	Name	Effect
`++x`	Pre-increment	Increments x by one, then returns x
`x++`	Post-increment	Returns x, then increments x by one
`--x`	Pre-decrement	Decrements x by one, then returns x
`x--`	Post-decrement	Returns x, then decrements x by one

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

Example

Try this code »

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

JavaScript Logical Operators

Logical operators are usually employed to combine conditional statements.

Operator	Name	Example	Result
`&&`	And	`x && y`	True if both x and y are true
`\|\|`	Or	`x \|\| y`	True if either x or y is true
`!`	Not	`!x`	True if x is not true

The following example will demonstrate how these logical operators actually function:

Example

Try this code »

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.");
}

You'll explore conditional statements in the JavaScript if/else chapter.

JavaScript Comparison Operators

Comparison operators are employed to compare two values in a Boolean manner.

Operator	Name	Example	Result
`==`	Equal	`x == y`	True if x is equal to y
`===`	Identical	`x === y`	True if x is equal to y, and they are of the same type
`!=`	Not equal	`x != y`	True if x is not equal to y
`!==`	Not identical	`x !== y`	True if x is not equal to y, or they are not of the same type
`<`	Less than	`x < y`	True if x is less than y
`>`	Greater than	`x > y`	True if x is greater than y
`>=`	Greater than or equal to	`x >= y`	True if x is greater than or equal to y
`<=`	Less than or equal to	`x <= y`	True if x is less than or equal to y

The following example will demonstrate these comparison operators in use:

Example

Try this code »

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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