reactjs - Uncaught Error : Cannot add node 1 because a node with that id is already in the Store

Question

在尝试使用该函数时，我收到一个错误，如 Uncaught Error: Cannot add node 1 because a node with that id is already in the Store.。

这是我的功能:

import { useEffect, useState } from "react";
import "./styles.css";

export default function App() {
  const [value, setValue] = useState(0);
  const slides = ["one", "two", "thre"];
  let size = slides.length;

  useEffect(() => {
    setValue(size);
  }, [size]);

  const prev = () => {
    if (size && size < 1 && size && size > slides.length) return;
    size--;
  };

  const next = () => {
    if (size && size < 1 && size && size > slides.length) return;
    size++;
  };

  return (
    <div className="slider">
      <a href="/" className="prev" onClick={prev}>
        Previous
      </a>
      <h2>Barking Road, London {value}</h2>
      <a href="/" className="next" onClick={next}>
        Next
      </a>
    </div>
  );
}

我想允许用户点击直到最小 1 和最大 3。但它不起作用。

LiveDemo

Answer 1

你实际上并不需要 useEffect为此，还要更改您的 <a>标记为 <button>

工作片段:

    function App() {
      const [value, setValue] = React.useState(1);
      const slides = ["one", "two", "thre"];

      const prev = () => {
        if (value > 1) setValue(value - 1);
      };

      const next = () => {
        if (value < slides.length) setValue(value + 1);
      };

      return (
        <div className="slider">
          <button className="prev" onClick={prev}>
            Previous
          </button>
          <h2>Barking Road, London {value}</h2>
          <button className="next" onClick={next}>
            Next
          </button>
        </div>
      );
    }

    const rootElement = document.getElementById("root");
    ReactDOM.render(<App />, rootElement);

    <script src="https://cdnjs.cloudflare.com/ajax/libs/react/17.0.2/umd/react.production.min.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/17.0.2/umd/react-dom.production.min.js"></script>
    <div id="root"></div>