Web/JavaScript/Reference/Classes/static

The static keyword defines a static method or property for a class. Neither static methods nor static properties can be called on instances of the class. Instead, they're called on the class itself. Static methods are often utility functions, such as functions to create or clone objects, whereas static properties are useful for caches, fixed-configuration, or any other data you don't need to be replicated across instances.

Syntax

static methodName() { ... }
static propertyName [= value];

Examples

Using static members in classes

The following example demonstrates several things:

How a static member (method or property) is defined on a class.
That a class with a static member can be sub-classed.
How a static member can and cannot be called.

class Triple {
  static customName = 'Tripler';
  static description = 'I triple any number you provide';
  static triple(n = 1) {
    return n * 3;
  }
}

class BiggerTriple extends Triple {
  static longDescription;
  static description = 'I square the triple of any number you provide';
  static triple(n) {
    return super.triple(n) * super.triple(n);
  }
}

console.log(Triple.description);   // 'I triple any number you provide'
console.log(Triple.triple());      // 3
console.log(Triple.triple(6));     // 18

var tp = new Triple();

console.log(BiggerTriple.triple(3));        // 81 (not affected by parent's instantiation)
console.log(BiggerTriple.description);      // 'I square the triple of any number you provide'
console.log(BiggerTriple.longDescription);  // undefined
console.log(BiggerTriple.customName);       // 'Tripler'

console.log(tp.triple());         // 'tp.triple is not a function'.

Calling static members from another static method

In order to call a static method or property within another static method of the same class, you can use the this keyword.

class StaticMethodCall {
  static staticProperty = 'static property';
  static staticMethod() {
    return 'Static method and ' + this.staticProperty + ' has been called';
  }
  static anotherStaticMethod() {
    return this.staticMethod() + ' from another static method';
  }
}
StaticMethodCall.staticMethod(); 
// 'Static method and static property has been called'

StaticMethodCall.anotherStaticMethod(); 
// 'Static method and static property has been called from another static method'

Calling static members from a class constructor and other methods

Static members are not directly accessible using the this keyword from non-static methods. You need to call them using the class name: CLASSNAME.STATIC_METHOD_NAME() / CLASSNAME.STATIC_PROPERTY_NAME or by calling the method as a property of the constructor: this.constructor.STATIC_METHOD_NAME() / this.constructor.STATIC_PROPERTY_NAME

class StaticMethodCall {
  constructor() {
    console.log(StaticMethodCall.staticProperty); // 'static property'
    console.log(this.constructor.staticProperty); // 'static property' 
    console.log(StaticMethodCall.staticMethod()); // 'static method has been called.' 
    console.log(this.constructor.staticMethod()); // 'static method has been called.' 
  }
 
  static staticProperty = 'static property';
  static staticMethod() {
    return 'static method has been called.';
  }
}

Specifications

Specification
ECMAScript (ECMA-262)The definition of 'Class definitions' in that specification.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
`static`	Chrome Full support 49 Full support 49 No support 42 — 49 Notes' Notes' Strict mode is required. No support 42 — 49 Disabled' Disabled' From version 42 until version 49 (exclusive): this feature is behind the `Experimental JavaScript` preference (needs to be set to `Enabled`). To change preferences in Chrome, visit chrome://flags.	Edge Full support 13	Firefox Full support 45	IE No support No	Opera Full support 36 Full support 36 No support 29 — 36 Notes' Notes' Strict mode is required. No support 29 — 36 Disabled' Disabled' From version 29 until version 36 (exclusive): this feature is behind the `Experimental JavaScript` preference (needs to be set to `Enabled`).	Safari Full support 9	WebView Android Full support 49 Full support 49 No support 42 — 49 Notes' Notes' Strict mode is required.	Chrome Android Full support 49 Full support 49 No support 42 — 49 Notes' Notes' Strict mode is required. No support 42 — 49 Disabled' Disabled' From version 42 until version 49 (exclusive): this feature is behind the `Experimental JavaScript` preference (needs to be set to `Enabled`). To change preferences in Chrome, visit chrome://flags.	Firefox Android Full support 45	Opera Android Full support 36 Full support 36 No support 29 — 36 Notes' Notes' Strict mode is required. No support 29 — 36 Disabled' Disabled' From version 29 until version 36 (exclusive): this feature is behind the `Experimental JavaScript` preference (needs to be set to `Enabled`).	Safari iOS Full support 9	Samsung Internet Android Full support 5.0 Full support 5.0 No support 4.0 — 5.0 Notes' Notes' Strict mode is required.	nodejs Full support 6.0.0 Full support 6.0.0 Full support 4.0.0 Disabled' Disabled' From version 4.0.0: this feature is behind the `--use_strict` runtime flag. Full support 5.0.0 Disabled' Disabled' From version 5.0.0: this feature is behind the `--harmony` runtime flag.

Legend

Full support: Full support
No support: No support
See implementation notes.': See implementation notes.
User must explicitly enable this feature.': User must explicitly enable this feature.