Expressions and operators - JavaScript | MDN

HTML: Markup language
CSS: Styling language
JavaScript: Scripting language
Web APIs: Programming interfaces
Learn web development
Get to know MDN better
This chapter documents all the JavaScript language operators, expressions and keywords.
For an alphabetical listing see the sidebar on the left.
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.
Template literal syntax.
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.
The import.defer() syntax loads a module dynamically, deferring synchronous evaluation until the returned namespace's properties are accessed.
The import.source() syntax results in an object representing the module's compiled source, without loading its dependencies, linking it, or evaluating it.
Postfix/prefix increment and postfix/prefix decrement operators.
Postfix increment operator.
Postfix decrement operator.
Prefix increment operator.
Prefix decrement operator.
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.