Factory pattern TypeScript example.

AbstractDialog.ts

import Button from "../buttons/button.interface";

export default abstract class Dialog {
    constructor() {}

    public renderWindow(): void {
        const okButton: Button = this.createButton();
        okButton.render();
    }

    public abstract createButton(): Button;
}

button.interfaces.ts

export default interface Button {
    render(): void;
    onClick(): void;
}

demo.ts

import Dialog from "./factory/AbstractDialog";
import HtmlDialog from "./factory/HtmlDialog";
import JavaDialog from "./factory/JavaDialog";

export default class RunDemo {

    constructor(private dialog: Dialog,
                private dialogType: 'HTML' | 'JAVA') {}

    private configure(): void {
        if (this.dialogType === 'HTML') {
            this.dialog = new HtmlDialog();
        } else {
            this.dialog = new JavaDialog();
        }
    }

    private runBusinessLogic(): void {
        this.dialog.renderWindow();
    }

    public mainProcess(): void {
        this.configure();
        this.runBusinessLogic();
    }
}

html_button.ts

import Button from "./button.interface";

export default class HtmlButton implements Button {
    constructor() {}
    
    render(): void {
        console.log('HTML button was rendered!');
    }

    onClick(): void {
        console.log('HTML onClick event was fired!');
    }
}

HtmlDialog.ts

import AbstractDialog from "./AbstractDialog";
import HtmlButton from "../buttons/html_button";

import Button from "../buttons/button.interface";

export default class HtmlDialog extends AbstractDialog {
    constructor() { super() }

    public createButton(): Button {
        return new HtmlButton();
    }
}

java_button.ts

import Button from "./button.interface";

export default class JavaButton implements Button {
    constructor() {}
    
    render(): void {
        console.log('There is a lot of stuff to render Java button!!!');
    }

    onClick(): void {
        console.log('JAVA onClick event was fired!( A LOT OF STUFF WERE USED!!!)');
    }
}

JavaDialog.ts

import AbstractDialog from "./AbstractDialog";
import JavaButton from "../buttons/java_button";

import Button from "../buttons/button.interface";

export default class JavaDialog extends AbstractDialog {
    constructor() { super() }

    public createButton(): Button {
        return new JavaButton();
    }
}