React

class HelloMessage extends React.Component {
  render() {
    return (
      <div>
        שלום {this.props.name}
      </div>
    );
  }
}

ReactDOM.render(
  <HelloMessage name="יהונתן" />,
  document.getElementById('hello-example')
);

class Timer extends React.Component {
  constructor(props) {
    super(props);
    this.state = { seconds: 0 };
  }

  tick() {
    this.setState(state => ({
      seconds: state.seconds + 1
    }));
  }

  componentDidMount() {
    this.interval = setInterval(() => this.tick(), 1000);
  }

  componentWillUnmount() {
    clearInterval(this.interval);
  }

  render() {
    return (
      <div dir='rtl'>
        שניות: {this.state.seconds}
      </div>
    );
  }
}

root.render(<Timer />);

class TodoApp extends React.Component {
  constructor(props) {
    super(props);
    this.state = { items: [], text: '' };
    this.handleChange = this.handleChange.bind(this);
    this.handleSubmit = this.handleSubmit.bind(this);
  }

  render() {
    return (
      <div dir='rtl'>
        <h3>משימות</h3>
        <TodoList items={this.state.items} />
        <form onSubmit={this.handleSubmit}>
          <label htmlFor="new-todo">
            רשימת המשימות
          </label>
          <input
            id="new-todo"
            onChange={this.handleChange}
            value={this.state.text}
          />
          <button>
            הוסף #{this.state.items.length + 1}
          </button>
        </form>
      </div>
    );
  }

  handleChange(e) {
    this.setState({ text: e.target.value });
  }

  handleSubmit(e) {
    e.preventDefault();
    if (this.state.text.length === 0) {
      return;
    }
    const newItem = {
      text: this.state.text,
      id: Date.now()
    };
    this.setState(state => ({
      items: state.items.concat(newItem),
      text: ''
    }));
  }
}

class TodoList extends React.Component {
  render() {
    return (
      <ul>
        {this.props.items.map(item => (
          <li key={item.id}>{item.text}</li>
        ))}
      </ul>
    );
  }
}

root.render(<TodoApp />);

class MarkdownEditor extends React.Component {
  constructor(props) {
    super(props);
    this.md = new Remarkable();
    this.handleChange = this.handleChange.bind(this);
    this.state = { value: 'שלום, **עולם**!' };
  }

  handleChange(e) {
    this.setState({ value: e.target.value });
  }

  getRawMarkup() {
    return { __html: this.md.render(this.state.value) };
  }

  render() {
    return (
      <div className="MarkdownEditor" dir='rtl'>
        <h3>קלט</h3>
        <label htmlFor="markdown-content">
          הקלד איזשהו markdown
        </label>
        <textarea
          id="markdown-content"
          onChange={this.handleChange}
          defaultValue={this.state.value}
        />
        <h3>פלט</h3>
        <div
          className="content"
          dangerouslySetInnerHTML={this.getRawMarkup()}
        />
      </div>
    );
  }
}

root.render(<MarkdownEditor />);