How to pass an event handler to a child component in React

Question

I have a <Button /> component I've created in React that abstracts out some of the styling in my application. I am using it in two different contexts - one to submit a login form, and the other to navigate to the registration page (and probably other contexts in the future).

I am trying to figure out how to pass the event handlers from the parent component to the <Button />. I want to call an onSubmit handler for the login form, but an onClick handler for the navigation button. Is this possible?

I have tried calling the component like this:

<Button text={callToAction} style={styles.callToActionButton} onClick={() => FlowRouter.go("Auth")}/>

<Button text="Go!" style={styles.registerButton} onSubmit={() => this.register(this.state.user, this.state.password)}/>

I've also tried removing the arrow function, which just causes the functions to execute when the component is loaded:

// executes event handlers on page load
<Button text={callToAction} style={styles.callToActionButton} onClick={FlowRouter.go("Auth")}/>

<Button text="Go!" style={styles.registerButton} onSubmit={this.register(this.state.user, this.state.password)}/>

Answer 1

In general, you can forward the onClick handler to your button class by passing it as a property. You could this make a required prop by simply defining the propTypes for your button component.

As an example, I added a small snippet that shows how it works

var StyledButton = React.createClass({
  propTypes: {
    // the StyledButton requires a clickHandler
    clickHandler: React.PropTypes.func.Required,
    // and I guess the text can be seen as required as well
    text: React.PropTypes.string.required
  },
  render: function() {
    // as you are sure you have a clickHandler, you can just reference it directly from the props
    return <button type="button" onClick={this.props.clickHandler}>{this.props.text}</button>;
  }
});

var MyForm = React.createClass({
  getInitialState() {
    return {
      clicked: 0
    };
  },
  click() {
    this.setState({clicked: this.state.clicked+1});
  	alert('ouch');
  },
  secondClickHandler() {
    this.setState({clicked: 0});
    alert(':(');
  },
  render() {
    // your parent component simply sets which button  
    return <fieldset>
        <div>
    	  <StyledButton clickHandler={this.click} text="Click me" /> 
          { (this.state.clicked > 0) && <StyledButton clickHandler={this.secondClickHandler} text="Not again" /> }
        </div>
    </fieldset>;
  }
});

ReactDOM.render(
  <MyForm />,
  document.getElementById('container')
);

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.0.2/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.0.2/react-dom.min.js"></script>
<div id="container">
    <!-- This element's contents will be replaced with your component. -->
</div>

Also, you wouldn't in general use the submit method of a button, you would rather send the data received to a webservice, and handle any changes when the result is received. The submit kills the current website and needs to load everything anew, while with an ajax call, or a store, it can just wait for the result and then redirect the user based on the response

Answer 2

How we have handled this is we have a button component that renders an a tag and then we have a href prop and a onClick prop you can pass in. If its a link just pass in the href prop to the button and if you are wanting it to execute a function just pass it in an onClick prop and make sure it gets set on the a tag.

In the Button component we also setup a custom onClick function that looks like this:

_onClick: function(e) {
  if (!this.props.onClick) {
    return; 
  }
  this.props.onClick(e);
}

and then on the a tag

<a href={this.props.href} onClick={this._onClick} />