TypeError：react__WEBPACK_IMPORTED_MODULE_6 ___ default.a.useState不是一个函数

Question

Below I provide a simplified sketch of my ReactJS code (based on material-ui ). This code does not compile, because probably I added function handleClickOpen() and function handleClose() in a wrong place. How can I fix it?

In particular, the following is the error message:

TypeError: react__WEBPACK_IMPORTED_MODULE_6___default.a.useState is not a function

import React, { Component, Fragment } from 'react';
import Slide from '@material-ui/core/Slide';


const Transition = React.forwardRef(function Transition(props, ref) {
  return <Slide direction="up" ref={ref} {...props} />;
});


class BottomControls extends Component {
    render() {

        const [open, setOpen] = React.useState(false);

        function handleClickOpen() {
          setOpen(true);
        }

        function handleClose() {
          setOpen(false);
        }

        return (
          <Fragment>
             # ...
          </Fragment>
        );
    }
}

export default BottomControls;

Answer 1

1. Hooks like useState are only for functional components

2. They should be called outside of the render function

3. React and react-dom need to be version 16.8 or higher

import React, { useState, Fragment } from 'react';
import Slide from '@material-ui/core/Slide';


const Transition = React.forwardRef(function Transition(props, ref) {
  return <Slide direction="up" ref={ref} {...props} />;
});


function BottomControls(props) {
  const [open, setOpen] = React.useState(false);
  function handleClickOpen() { setOpen(true); }
  function handleClose() { setOpen(false); }
  return (
    <Fragment>
      // whatever
    </Fragment>
  )
}

export default BottomControls;

Answer 2

根据React文档，我们不能在基于类的组件内部使用钩子，请参考以下URL https://reactjs.org/docs/hooks-faq.html