React组件间通信：从子组件向父组件传递数据并触发API请求

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

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

    // 读取表单数据
    const form = e.target;
    const inputVal = form.myInput.value;

    console.log("Input value from child:", inputVal);

    // 调用父组件传入的回调函数，并传递输入值
    if (onSubmit) { // 确保 onSubmit 存在
      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() {
  // token fetch 相关状态
  const [tokens, setTokens] = useState([]);
  const [loading, setLoading] = useState(false);
  // 新增状态：用于存储从 InputField 接收到的搜索值
  const [searchValue, setSearchValue] = useState(null); 

  // 处理 InputField 提交的回调函数
  const handleSearchSubmit = (val) => {
    setSearchValue(val); // 更新 searchValue 状态
  };

  useEffect(() => {
    // 只有当 searchValue 有效时才执行 fetch 请求
    if (searchValue) { 
      setLoading(true);
      fetch(`https://api.multiversx.com/accounts/${searchValue}/tokens`) // 使用 searchValue 构建 URL
        .then(response => response.json())
        .then(json => setTokens(json))
        .finally(() => {
          setLoading(false);
        });
      console.log("Fetching tokens for:", searchValue); 
    } else {
      // 如果 searchValue 为空，可以清空 tokens 或显示提示
      setTokens([]); 
    }
  }, [searchValue]); // 将 searchValue 添加到依赖数组，当它变化时重新执行 useEffect

  // ... 其他辅助函数（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">
                {/* 正确地渲染 InputField 组件，并传递回调函数 */}
                <InputField onSubmit={handleSearchSubmit} /> 
            </div>
            {/* 可以显示当前的搜索值，例如： */}
            <p>Current Search Value: {searchValue || "None"}</p>
        </div>
        <div className="down-side">
            <table className="Token-section-output">
              {loading ? (
                <div>Loading...</div>
              ) : (
                <>
                  <h1>Tokens</h1>
                  {/* ... tokens 列表渲染逻辑 ... */}
                  <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.length > 0 ? (
                      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>
                      ))
                    ) : (
                      <tr><td colSpan="3">No tokens found or no search value provided.</td></tr>
                    )}
                  </table>
                </>
              )}
            </table>
        </div>   
    </content>
  );
}

export default App;