[Docs] Accessibility : Should add aria-expanded and aria-controls for Collapse toggle

For accessibility we should add aria-expanded and aria-controls for Collapse toggle: https://react-bootstrap.github.io/components.html#transitions-collapse

class Example extends React.Component {
  constructor(...args) {
    super(...args);

    this.state = {};
  }

  render() {
    return (
      <div>
        <Button onClick={ ()=> this.setState({ open: !this.state.open })}>
          click
        </Button>
        <Collapse in={this.state.open}>
          <div>
            <Well>
              Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry richardson ad squid.
              Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt sapiente ea proident.
            </Well>
          </div>
        </Collapse>
      </div>
    );
  }
}

ReactDOM.render(<Example/>, mountNode);

The accessible one:

class Example extends React.Component {
  constructor(...args) {
    super(...args);

    this.state = {
        open: false
    };
  }

  render() {
    return (
      <div>
        <Button onClick={ ()=> this.setState({ open: !this.state.open })} aria-expanded={this.state.open} aria-controls="collapseExample">
          click
        </Button>
        <Collapse in={this.state.open}>
          <div id="collapseExample">
            <Well>
              Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry richardson ad squid.
              Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt sapiente ea proident.
            </Well>
          </div>
        </Collapse>
      </div>
    );
  }
}

ReactDOM.render(<Example/>, mountNode);

Bootstrap example: https://getbootstrap.com/docs/4.0/components/collapse/

[jquense]

yup! please go for it 👍

[taion]

We’re definitely open to PRs here.