反应：如何有条件地渲染？

Question

I have three components A, B & C.

I have two flags showA & showB.

• If ShowA and ShowB are false then render C.
• If ShowA is true only then render A.
• If showB is true only then render B.

How do i achieve this?

Answer 1

You can achieve it in different ways.

Multiple returns

render() {
    const { showA, showB } = this.state;
    if (showA) return <A />
    if (showB) return <B />
    return <C />
}

Inline if with the '&&' operator

render() {
    const { showA, showB } = this.state;
    return (
        <div>
            {(showA && !showB) && <A />}
            {(showB && !showA) && <B />}
            {(!showA && !showB) && <C />}
        </div>
    )
}

See also: https://reactjs.org/docs/conditional-rendering.html

Answer 2

  class APP extends React.Component {
    constructor() {
      super();
      this.state = { showA: false, showB: false };
    }

    render() {
      const {showA, showB} = this.state;
      return [showA && <A/>, showB && <B />];
   }
 }

Answer 3

I guess you meant show C component when showA and showB are both false

Assuming that your showA and showB are state properties:

render() {
  return (
    this.state.showA 
    ? <A />
    : this.state.showB ? <B />
    : <C />
  )
}