React组件间通信：从子组件向父组件传递数据实践

// InputField.js
import React from 'react';

export default function InputField({ onSubmit }) { // 接收一个名为 onSubmit 的 prop
  function handleSubmit(e) {
    e.preventDefault(); // 阻止浏览器默认的表单提交行为

    const form = e.target;
    const inputVal = form.myInput.value; // 获取输入框的值

    console.log("子组件获取到的输入值:", inputVal);

    // 调用父组件传递进来的回调函数，并将输入值作为参数传递
    if (onSubmit && typeof onSubmit === 'function') {
      onSubmit(inputVal); 
    }
  }

  return (
    <form method="post" onSubmit={handleSubmit}>
      <input name="myInput" id="adress-field" placeholder="Enter adress" autoComplete="on" />
      <button type="submit" id="adress-button">Send</button>
    </form>
  );
}

// App.js
import './App.css';
import AccountNumber from "./components/AccountNumber";
import InputField from "./components/InputField";
import { useEffect, useState } from "react";

function App() {
  // 状态用于存储从 InputField 接收到的地址值
  const [searchValue, setSearchValue] = useState(null); 

  // 状态用于存储API返回的tokens数据
  const [tokens, setTokens] = useState([]);
  // 状态用于管理加载状态
  const [loading, setLoading] = useState(false);

  // 定义一个回调函数，用于接收 InputField 传递过来的值
  const handleSearchSubmit = (val) => {
    setSearchValue(val); // 更新 searchValue 状态
  };

  // useEffect 钩子用于在 searchValue 变化时触发数据请求
  useEffect(() => {
    // 只有当 searchValue 不为 null 且不为空字符串时才进行数据请求
    if (searchValue) { 
      setLoading(true);
      fetch(`https://api.multiversx.com/accounts/${searchValue}/tokens`)
        .then(response => response.json())
        .then(json => setTokens(json))
        .finally(() => {
          setLoading(false);
        });
      console.log("App组件发起请求，searchValue:", searchValue);
    }
    // 依赖数组包含 searchValue，确保当 searchValue 改变时 useEffect 重新运行
  }, [searchValue]); 

  // ... (其他辅助函数，如 round, numberWithSpaces 保持不变)

  return (
    <content className="content">
        <div className="up-side">
            <div className="account-number-box">
                <p id="p-account-number">Total number of accounts</p>
                <p id="account-number"><AccountNumber/></p>
            </div>
            <div className="adress-search">
                {/* 将 handleSearchSubmit 函数作为 onSubmit prop 传递给 InputField */}
                <InputField onSubmit={handleSearchSubmit} /> 
            </div>
            {/* 可以显示当前 searchValue 进行调试 */}
            <p>当前搜索地址: {searchValue || '未输入'}</p>
        </div>
        <div className="down-side">
            <table className="Token-section-output">
              {loading ? (
                <div>Loading...</div>
              ) : (
                <>
                  <h1>Tokens</h1>
                  <table className='Token-section-output' border={0}>
                    <tr className='token-row-type'>
                      <th className='token-column'>Name</th>
                      <th className='center-column'>Price</th>
                      <th>Hold</th>
                    </tr>
                    <tr className="space20"/>
                    {tokens.map(token => (
                      <tr className='token-row' key={token.id}>
                        <td className='token-column'>
                        <img className="img-Tokens" src = {token?.assets?.pngUrl ?? "img/Question.png"} /> 
                          <p>{token.name}</p> 
                        </td>
                        <td className='center-column'> <p>${round(token.price, 10000000)}</p> </td>
                        <td> 
                          <p>{round(token.balance / Math.pow(10, token.decimals), 10000000)}</p> 
                          <p className='token-hold'>${round(token.valueUsd, 10000000)}</p>
                        </td>
                      </tr>
                    ))}
                  </table>
                </>
              )}
            </table>
        </div>   
    </content>
  );
}

// 辅助函数（保持不变）
function round(nr, ten) { 
    return Math.round(nr * ten) / ten;
}

function numberWithSpaces(nr) { 
    return nr.toString().replace(/\B(?=(\d{3})+(?!\d))/g, " ");
}

export default App;