All operators in javascript

Expressions and operators

This chapter documents all the JavaScript language operators, expressions and keywords.

Expressions and operators by category

For an alphabetical listing see the sidebar on the left.

Primary expressions

Basic keywords and general expressions in JavaScript. These expressions have the highest precedence (higher than operators).

The this keyword refers to a special property of an execution context.

Basic null , boolean, number, and string literals.

Array initializer/literal syntax.

Object initializer/literal syntax.

The function keyword defines a function expression.

The class keyword defines a class expression.

The function* keyword defines a generator function expression.

The async function defines an async function expression.

The async function* keywords define an async generator function expression.

Regular expression literal syntax.

Left-hand-side expressions

Left values are the destination of an assignment.

Member operators provide access to a property or method of an object ( object.property and object[«property»] ).

The optional chaining operator returns undefined instead of causing an error if a reference is nullish ( null or undefined ).

The new operator creates an instance of a constructor.

In constructors, new.target refers to the constructor that was invoked by new .

An object exposing context-specific metadata to a JavaScript module.

The super keyword calls the parent constructor or allows accessing properties of the parent object.

The import() syntax allows loading a module asynchronously and dynamically into a potentially non-module environment.

Increment and decrement

Postfix/prefix increment and postfix/prefix decrement operators.

Postfix increment operator.

Postfix decrement operator.

Prefix increment operator.

Prefix decrement operator.

Unary operators

A unary operation is an operation with only one operand.

The delete operator deletes a property from an object.

The void operator evaluates an expression and discards its return value.

The typeof operator determines the type of a given object.

The unary plus operator converts its operand to Number type.

The unary negation operator converts its operand to Number type and then negates it.

Pause and resume an async function and wait for the promise’s fulfillment/rejection.

Arithmetic operators

Arithmetic operators take numerical values (either literals or variables) as their operands and return a single numerical value.

Relational operators

A comparison operator compares its operands and returns a boolean value based on whether the comparison is true.

Less than or equal operator.

Greater than or equal operator.

The instanceof operator determines whether an object is an instance of another object.

The in operator determines whether an object has a given property.

Note: => is not an operator, but the notation for Arrow functions.

Equality operators

The result of evaluating an equality operator is always of type boolean based on whether the comparison is true.

Strict inequality operator.

Bitwise shift operators

Operations to shift all bits of the operand.

Bitwise left shift operator.

Bitwise right shift operator.

Bitwise unsigned right shift operator.

Binary bitwise operators

Bitwise operators treat their operands as a set of 32 bits (zeros and ones) and return standard JavaScript numerical values.

Binary logical operators

Logical operators implement boolean (logical) values and have short-circuiting behavior.

Nullish Coalescing Operator.

Conditional (ternary) operator

The conditional operator returns one of two values based on the logical value of the condition.

Assignment operators

An assignment operator assigns a value to its left operand based on the value of its right operand.

Unsigned right shift assignment.

Nullish coalescing assignment.

Destructuring assignment allows you to assign the properties of an array or object to variables using syntax that looks similar to array or object literals.

Yield operators

Pause and resume a generator function.

Delegate to another generator function or iterable object.

Spread syntax

Spread syntax allows an iterable, such as an array or string, to be expanded in places where zero or more arguments (for function calls) or elements (for array literals) are expected. In an object literal, the spread syntax enumerates the properties of an object and adds the key-value pairs to the object being created.

Comma operator

The comma operator allows multiple expressions to be evaluated in a single statement and returns the result of the last expression.

Specifications

Browser compatibility

BCD tables only load in the browser

See also

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JavaScript Operators

The Assignment Operator = assigns a value to a variable.

JavaScript Assignment

The Assignment Operator ( = ) assigns a value to a variable:

Assignment Examples

// Assign the value 5 to x
let x = 5;
// Assign the value 2 to y
let y = 2;
// Assign the value x + y to z:
let z = x + y;

JavaScript Addition

The Addition Operator ( + ) adds numbers:

Adding

JavaScript Multiplication

The Multiplication Operator ( * ) multiplies numbers:

Multiplying

Types of JavaScript Operators

There are different types of JavaScript operators:

• Arithmetic Operators
• Assignment Operators
• Comparison Operators
• String Operators
• Logical Operators
• Bitwise Operators
• Ternary Operators
• Type Operators

JavaScript Arithmetic Operators

Arithmetic Operators are used to perform arithmetic on numbers:

Arithmetic Operators Example

Operator	Description
+	Addition
—	Subtraction
*	Multiplication
**	Exponentiation (ES2016)
/	Division
%	Modulus (Division Remainder)
++	Increment
—	Decrement

Note

Arithmetic operators are fully described in the JS Arithmetic chapter.

JavaScript Assignment Operators

Assignment operators assign values to JavaScript variables.

The Addition Assignment Operator ( += ) adds a value to a variable.

Assignment

Operator	Example	Same As
=	x = y	x = y
+=	x += y	x = x + y
-=	x -= y	x = x — y
*=	x *= y	x = x * y
/=	x /= y	x = x / y
%=	x %= y	x = x % y
**=	x **= y	x = x ** y

Note

Assignment operators are fully described in the JS Assignment chapter.

JavaScript Comparison Operators

Operator	Description
==	equal to
===	equal value and equal type
!=	not equal
!==	not equal value or not equal type
>	greater than
	less than
>=	greater than or equal to
	less than or equal to
?	ternary operator

Note

Comparison operators are fully described in the JS Comparisons chapter.

JavaScript String Comparison

All the comparison operators above can also be used on strings:

Example

Note that strings are compared alphabetically:

Example

JavaScript String Addition

The + can also be used to add (concatenate) strings:

Example

The += assignment operator can also be used to add (concatenate) strings:

Example

The result of text1 will be:

Note

When used on strings, the + operator is called the concatenation operator.

Adding Strings and Numbers

Adding two numbers, will return the sum, but adding a number and a string will return a string:

Example

The result of x, y, and z will be:

Note

If you add a number and a string, the result will be a string!

JavaScript Logical Operators

Note

Logical operators are fully described in the JS Comparisons chapter.

JavaScript Type Operators

Operator	Description
typeof	Returns the type of a variable
instanceof	Returns true if an object is an instance of an object type

Note

Type operators are fully described in the JS Type Conversion chapter.

JavaScript Bitwise Operators

Bit operators work on 32 bits numbers.

Any numeric operand in the operation is converted into a 32 bit number. The result is converted back to a JavaScript number.

Operator	Description	Example	Same as	Result	Decimal
&	AND	5 & 1	0101 & 0001	0001	1
|	OR	5 | 1	0101 | 0001	0101	5
~	NOT	~ 5	~0101	1010	10
^	XOR	5 ^ 1	0101 ^ 0001	0100	4
	left shift	5	0101	1010	10
>>	right shift	5 >> 1	0101 >> 1	0010	2
>>>	unsigned right shift	5 >>> 1	0101 >>> 1	0010	2

The examples above uses 4 bits unsigned examples. But JavaScript uses 32-bit signed numbers.
Because of this, in JavaScript, ~ 5 will not return 10. It will return -6.
~00000000000000000000000000000101 will return 11111111111111111111111111111010

Bitwise operators are fully described in the JS Bitwise chapter.

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