in-react.jsx

const BadGoose = () => (<div>shown!</div>)
                                
const App = (props) => {
  const [toggle, setToggle] = useState(true)
  
  return (<div>
    <button onClick={() => setToggle(!toggle)}>click me</div>
    { toggle ? <BadGoose /> : null }
  </div>)
}

in-vue.js

const BadGoose = {
  template: '<div>shown!</div>',
}

const App = {
  components: { BadGoose },
  
  template: `<div>
    <button @click="toggle = !toggle">click me</button>
    <bad-goose  v-if="toggle" />
  </div>`,

  data: () => ({ toggle: true })
})