Statické metody JavaScriptu

Obsah

Metody statické třídy jsou definovány na samotné třídě.

statickou metodu nemůžete volat na objekt, pouze na třídu objektu.

Příklad

class Car {
  constructor(name) {
    this.name = 
  name;	  }
  static hello() {
    return "Hello!!";	  }
}
const myCar = new Car("Ford");
// You can call 'hello()' on 
  the Car Class:
document.getElementById("demo").innerHTML 
  = Car.hello();
// But NOT on a Car Object:
// document.getElementById("demo").innerHTML 
  = myCar.hello();
// this will raise an error.

Zkuste to sami →

<!DOCTYPE html>
<html>
<body>
<h1>JavaScript Class Static Methods</h1>
<p>A static method is created with the "static" keyword, and you can only call the method on the class itself.</p>

<p id="demo"></p>

<script>
class Car {
  constructor(name) {
    this.name = name;
  }
  static hello() {
    return "Hello!!";
  }
}

const myCar = new Car("Ford");

//You can call 'hello()' on the Car Class:
document.getElementById("demo").innerHTML = Car.hello();

// But NOT on  a Car Object:
// document.getElementById("demo").innerHTML = myCar.hello();
// this will raise an error.
</script>

</body>
</html>

Pokud chcete použít objekt myCar uvnitř statické metody, můžete jej odeslat jako parametr:

Příklad

class Car {
  constructor(name) {
    this.name = 
  name;	  }
  static hello(x) {
    return "Hello " + 
  x.name;	  }
}
const myCar = new Car("Ford");
document.getElementById("demo").innerHTML 
  = Car.hello(myCar);

Zkuste to sami →

<!DOCTYPE html>
<html>
<body>
<h1>JavaScript Class Static Methods</h1>
<p>To use the "myCar" object inside the static method, you can send it as parameter.</p>

<p id="demo"></p>

<script>
class Car {
  constructor(name) {
    this.name = name;
  }
  static hello(x) {
    return "Hello " + x.name;
  }
}

const myCar = new Car("Ford");
document.getElementById("demo").innerHTML = Car.hello(myCar);
</script>

</body>
</html>