示例

For example, you don’t need an Effect to adjust some state based on other state:

function Form() {
  const [firstName, setFirstName] = useState('Taylor');
  const [lastName, setLastName] = useState('Swift');
 
  // 🔴 Avoid: redundant state and unnecessary Effect
  const [fullName, setFullName] = useState('');
  useEffect(() => {
    setFullName(firstName + ' ' + lastName);
  }, [firstName, lastName]);
  // ...
}

上面的写法是多余的，和下面代码的作用完全一致：

function Form() {
  const [firstName, setFirstName] = useState('Taylor');
  const [lastName, setLastName] = useState('Swift');
  // ✅ Good: calculated during rendering
  const fullName = firstName + ' ' + lastName;
  // ...
}

base::函数组件的生命周期钩子