decorator_design_pattern.ts

interface Component { 
    operation(): void;
}

class ConcreteComponent implements Component { 
    public operation() { 
        console.log('origin opration');
    }
}

abstract class Decorator implements Component {
    private component: Component
    public constructor(component: Component) {
        this.component = component;
    }
    public operation() { 
        this.component.operation();
    }
}

class ConcreteDecorator extends Decorator { 
    public constructor(component: Component) {
        super(component);
    }

    public operation():void { 
        super.operation();
        this.addedBehavior();
    }

    public addedBehavior(): void { 
        console.log('add behavior');
        // do something
    }
}

class ConcreteDecorator2 extends Decorator { 
    public constructor(component: Component) {
        super(component);
    }

    public operation():void { 
        super.operation();
    }
}

const component: Component = new ConcreteComponent();
const componentDecorated: Component = new ConcreteDecorator(component);
const componentDecorated2: Component = new ConcreteDecorator2(component);
componentDecorated.operation();
componentDecorated2.operation();