JavaScript에서 정적 변수는 어떻게 선언되고 사용됩니까?

function MyClass() {
  // Private variable
  var privateVariable = "foo";

  // Public variable
  this.publicVariable = "bar";

  // Public method
  this.privilegedMethod = function() {
    alert(privateVariable);
  };
}

// Static variable shared by all instances
MyClass.staticProperty = "baz";

class MyClass {
  constructor() {
    // Private variable
    const privateVariable = 'private value';

    // Public property
    this.publicVariable = 'public value';

    // Public method with access to private variable
    this.privilegedMethod = function() {
      console.log(privateVariable);
    };
  }

  // Prototype methods
  publicMethod() {
    console.log(this.publicVariable);
  }

  // Static property shared by all instances
  static staticProperty = 'static value';

  // Static method
  static staticMethod() {
    console.log(this.staticProperty);
  }
}