Question

我有一个使用钩子的React应用程序。我希望将slots状态在props中传递给其他组件。但是，我的其他组件仅返回undefined，并且在slots更改时不会触发道具更改。

应用程序：

   import React, { useState, useEffect } from 'react'
    import { render } from 'react-dom'
    import Pusher from 'pusher-js'
    import SlotMachine from './components/SlotMachine'

    const App = () => {
      const [ slots, setSlots ] = useState({});

      const pusher = new Pusher('XXXXXXX', {
             cluster: 'xxx',
             encrypted: true
           });

      const channel = pusher.subscribe('my-channel');
         channel.bind('my-event', data => {
           console.log(`Got data from pusher ${data}`);
           setSlots(data);
           console.log(data);
         });

         useEffect(()=>{
           console.log(`Slots with channel changes: ${slots}`);
           console.log(slots);
           **//shows it changes! BUT doesn't seem to actually pass down into props of SlotMachine component**
         }, [slots])

      return(
        <div>
          <SlotMachine props={slots}/>
        </div>
      );
    };

    render(<App />, document.getElementById('root'));

SlotMachine组件：

import React, { useEffect, useRef, useState } from 'react'
import './slots.css'

function rnd(min, max) {
  return Math.floor(Math.random() * (max - min)) + min
}

//slots is a prop as an array of three
//check if slots is empty or if button is clicked
const SlotMachine = (props) => {
    const ringElements = useRef();
    const [rings, updateRings] = useState([]);
    const [manual, buttonClick] = useState(true);
    const [ slots, setSlots ] = useState(props.slots);

    const slotMap = {
      0: 360,
      1: 120,
      2: 180,
      3: 240,
      4: 300,
      5: 0
    };

    //shows up as undefined when first renders but doesn't show up ever again 
    useEffect(() => {
      console.log(`props changed: ${props.slots}`)
      console.log(props.slots);
    }, [props]);

    useEffect(()=>{
      console.log(`Props Change: ${props.slots}`);
      if(props.slots !== undefined ) {
        console.log(`API Hit: ${props.slots}`);
        buttonClick(false);
        setSlots(props.slots);
        rotate()
      }
    }, [props.slots]);

    const rotate = () => { ... }, [rings]); //not important rn

    useEffect(() =>  { ... }, [ringElements]);

    return(
      <div>
        <div className="slots">
        <div className="rings" ref={ringElements}>
          <div className="ring">
            <div className="slot" id="0">60</div>
            <div className="slot" id="1">120</div>
            <div className="slot" id="2">180</div>
            <div className="slot" id="3">240</div>
            <div className="slot" id="4">300</div>
            <div className="slot" id="5">360</div>
          </div>
          <div className="ring">
            <div className="slot" id="0">0</div>
            <div className="slot" id="1">1</div>
            <div className="slot" id="2">2</div>
            <div className="slot" id="3">3</div>
            <div className="slot" id="4">3</div>
            <div className="slot" id="5">4</div>
          </div>
          <div className="ring">
            <div className="slot" id="0">0</div>
            <div className="slot" id="1">1</div>
            <div className="slot" id="2">2</div>
            <div className="slot" id="3">3</div>
            <div className="slot" id="4">3</div>
            <div className="slot" id="5">4</div>
          </div>
        </div>
      </div>
      <button className="spin-button" onClick={() => { buttonClick(true); rotate();} }>SPIN</button>
    </div>

  );
}

export default SlotMachine

Answer 1

您正在传递slots作为道具props：

<SlotMachine props={slots}/>

您需要将其传递为slots：

<SlotMachine slots={slots}/>

React Hooks状态更改未通过适当的支持

1 个答案: