123 123

let Form = React.createClass({
  getInitialState() {
    return {
      fieldsCount: 1
    };
  },
  _addField() {
    this.setState({ fieldsCount: this.state.fieldsCount + 1 });
  },
  render() {
    let fields = [];

    for (let i = 0; i < this.state.fieldsCount; i++) {
      fields.push(<input />);
    }

    return (
      <form>
        {fields}
        <button onClick={this._addField}>+</button>
      </form>
    );
  }
});