如何在 map() function 中获取反应道具

Question

Suppose I have a react function with props active .

// About Page
export default function About() {
  return <Menu active="about" />;
}

// Menu Component
function Menu(props) {
  const items = ["home", "about", "services", "contact"];

  return (
    <nav>
      {items.map((item, index) => {
          console.log(props);
        return <li className={`${props.active === item && "active"}`}> {item} </li>;
      })}
    </nav>
  );
}

How do I get the props.active inside the map() function? it's returning undefined right now.

Answer 1

Converted to snippet, Seems props is getting correctly. (not related, but minor fix, if you use && in class name generation, for the falsy condition classname will be "false")

 function About() { return <Menu active="about" />; } function Menu(props) { const items = ["home", "about", "services", "contact"]; return ( <nav> {items.map((item, index) => { console.log(props); return ( <li className={`${props.active === item? "active": "inactive"}`}> {item} </li> ); })} </nav> ); } ReactDOM.render(<About />, document.getElementById('app'))

 .active { color: red }.inactive { color: grey }

 <script crossorigin src="https://unpkg.com/react@17/umd/react.development.js"></script> <script crossorigin src="https://unpkg.com/react-dom@17/umd/react-dom.development.js"></script> <div id="app"> </div>

Answer 2

The above sample code in question works flawlessly.

In my project, I was actually modifying the wrong page to provide props, thus got {}

So, I'm writing this answer so that other people won't spend time on it.