JavaScript Class static keyword

Definition and Usage

static The keyword for defining static methods in a class definition.

Static methods are directly on the class (in the example above, Car) call, without creating an instance/object of the class (mycar)

Instance

Example 1

Create a static method and call it on the class:

class Car {
  constructor(brand) {
    this.carname = brand;
  }
  static hello() {  // static method
    return "Hello!!";
  }
}
mycar = new Car("Ford");
//Call 'hello()' on the class Car:
document.getElementById("demo").innerHTML = Car.hello();
//Do not call on the 'mycar' object:
//document.getElementById("demo").innerHTML = mycar.hello();
//Will cause an error

亲自试一试

Example 2

If you want to use the mycar object inside a static method, you can send it as a parameter:

Send "mycar" as a parameter:
class Car {
  constructor(brand) {
    this.carname = brand;
  }
  static hello(x) {
    return "Hello " + x.carname;
  }
}
mycar = new Car("Ford");
document.getElementById("demo").innerHTML = Car.hello(mycar);

亲自试一试

语法

static methodName()

技术细节

JavaScript版本： ECMAScript 2015 (ES6)

浏览器支持

Keyword Chrome IE Firefox Safari Opera
static 49.0 13.0 45.0 9.0 36.0

相关页面

JavaScript教程：Classe JavaScript

JavaScript教程：JavaScript ES6 (EcmaScript 2015)

Manuale di riferimento JavaScript:Metodo constructor()