javascript - React.js: How to append a component on click?

Question

I'm new to React and I'm puzzled on something kind of basic.

I need to append a component to the DOM after the DOM is rendered, on a click event.

My initial attempt is as follows, and it doesn't work. But it's the best thing I've thought to try. (Apologies in advance for mixing jQuery with React.)

    ParentComponent = class ParentComponent extends React.Component {
      constructor () {
        this.addChild = this.addChild.bind(this);
      }

      addChild (event) {
        event.preventDefault();
        $("#children-pane").append(<ChildComponent/>);
      }

      render () {
        return (
          <div className="card calculator">
            <p><a href="#" onClick={this.addChild}>Add Another Child Component</a></p>
            <div id="children-pane">
              <ChildComponent/>
            </div>
          </div>
        );
      }
    };

Hopefully it's clear what I need to do, and I hope you can help me attain an appropriate solution.

Answer 1

Don't use jQuery to manipulate the DOM when you're using React. React components should render a representation of what they should look like given a certain state; what DOM that translates to is taken care of by React itself.

What you want to do is store the "state which determines what gets rendered" higher up the chain, and pass it down. If you are rendering n children, that state should be "owned" by whatever contains your component. eg:

class AppComponent extends React.Component {
  state = {
    numChildren: 0
  }

  render () {
    const children = [];

    for (var i = 0; i < this.state.numChildren; i += 1) {
      children.push(<ChildComponent key={i} number={i} />);
    };

    return (
      <ParentComponent addChild={this.onAddChild}>
        {children}
      </ParentComponent>
    );
  }

  onAddChild = () => {
    this.setState({
      numChildren: this.state.numChildren + 1
    });
  }
}

const ParentComponent = props => (
  <div className="card calculator">
    <p><a href="#" onClick={props.addChild}>Add Another Child Component</a></p>
    <div id="children-pane">
      {props.children}
    </div>
  </div>
);

const ChildComponent = props => <div>{"I am child " + props.number}</div>;