反應動態輸入表單顯示錯誤一些問題

我正在創建動態輸入欄位我正在驗證陣列中驗證輸出的一些必需欄位我嘗試在輸入中顯示錯誤值我導致了一些錯誤。我嘗試了一些與索引陣列的匹配，但我不作業

代碼沙盒：https ://codesandbox.io/s/floral-bash-lrvkc ? file =/ src/App.js:0-2399

感謝幫助

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

function App() {
  const [inputList, setInputList] = useState([{ firstName: "", lastName: "" }]);
  const [formError, setFormError] = useState([]);
  const [isSubmit, setisSubmit] = useState(false);

  // handle input change
  const handleInputChange = (e, index) => {
    const { name, value } = e.target;
    const list = [...inputList];
    list[index][name] = value;
    setInputList(list);
  };

  // handle click event of the Remove button
  const handleRemoveClick = (index) => {
    const list = [...inputList];
    list.splice(index, 1);
    setInputList(list);
  };

  // handle click event of the Add button
  const handleAddClick = () => {
    setInputList([...inputList, { firstName: "", lastName: "" }]);
  };
  const Submit = (e) => {
    e.preventDefault();
    const errorMsg = inputList.map((list, key) => {
      let error = {};
      if (!list.firstName) {
        error.errorfirstName = "FirstName is required";
      } else {
        error.errorfirstName = "";
      }
      if (!list.lastName) {
        error.errorlastName = "LastName is required";
      } else {
        error.errorlastName = "";
      }
      return error;
    });
    console.log(errorMsg);
    setFormError(errorMsg);
  };

  return (
    <div className="App">
      {inputList.map((x, i) => {
        return (
          <div className="box">
            <input
              name="firstName"
              placeholder="Enter First Name"
              value={x.firstName}
              onChange={(e) => handleInputChange(e, i)}
            />
            <input
              className="ml10"
              name="lastName"
              placeholder="Enter Last Name"
              value={x.lastName}
              onChange={(e) => handleInputChange(e, i)}
            />
            <div className="btn-box">
              {inputList.length !== 1 && (
                <button className="mr10" onClick={() => handleRemoveClick(i)}>
                  Remove
                </button>
              )}
              {inputList.length - 1 === i && (
                <button onClick={handleAddClick}>Add</button>
              )}
            </div>
          </div>
        );
      })}
      <button onClick={Submit}>Submit</button>
      <div style={{ marginTop: 20 }}>{JSON.stringify(inputList)}</div>
    </div>
  );
}

export default App;

uj5u.com熱心網友回復：

請看下面的代碼。我添加了一些代碼 - 見注釋// CHANGE HERE

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

function App() {
  const [inputList, setInputList] = useState([{ firstName: "", lastName: "" }]);
  const [formError, setFormError] = useState([]);
  const [isSubmit, setisSubmit] = useState(false);

  // handle input change
  const handleInputChange = (e, index) => {
    const { name, value } = e.target;
    const list = [...inputList];
    list[index][name] = value;
    setInputList(list);
  };

  // handle click event of the Remove button
  const handleRemoveClick = (index) => {
    const list = [...inputList];
    list.splice(index, 1);
    setInputList(list);
  };

  // handle click event of the Add button
  const handleAddClick = () => {
    setInputList([...inputList, { firstName: "", lastName: "" }]);
  };

  // CHANGE HERE: a flag to be set when there is an error
  var isError = false;

  const Submit = (e) => {
    e.preventDefault();
    const errorMsg = inputList.map((list, key) => {
      let error = {};
      if (!list.firstName) {
        error.errorfirstName = "FirstName is required";
        // CHANGE HERE: set error flag
        isError = true;
      } else {
        error.errorfirstName = "";
      }
      if (!list.lastName) {
        error.errorlastName = "LastName is required";
        // CHANGE HERE: set error flag
        isError = true;
      } else {
        error.errorlastName = "";
      }
      return error;
    });
    console.log(errorMsg);
    setFormError(errorMsg);
    // CHANGE HERE: return false and prevent form submission in case of errors
    if (isError)
      return false;
  };

  // CHANGE HERE: added Error function
  const Error = () => {
    return <>
      {formError.map((error, i) => {
        var str = error.errorfirstName   " "   error.errorlastName;
        if (str !== ' ')
          return <p key={i.toString()}> {i} {str}</p>;
        return <></>
      })}
    </>;
  };

  return (
    <div className="App">
      {inputList.map((x, i) => {
        return (
          <div className="box">
            <input
              name="firstName"
              placeholder="Enter First Name"
              value={x.firstName}
              onChange={(e) => handleInputChange(e, i)}
            />
            <input
              className="ml10"
              name="lastName"
              placeholder="Enter Last Name"
              value={x.lastName}
              onChange={(e) => handleInputChange(e, i)}
            />
            <div className="btn-box">
              {inputList.length !== 1 && (
                <button className="mr10" onClick={() => handleRemoveClick(i)}>
                  Remove
                </button>
              )}
              {inputList.length - 1 === i && (
                <button onClick={handleAddClick}>Add</button>
              )}
            </div>
          </div>
        );
      })}
      <button onClick={Submit}>Submit</button>
      // CHANGE HERE: show an error if any
      <Error />
      <div style={{ marginTop: 20 }}>{JSON.stringify(inputList)}</div>
    </div>
  );
}

export default App;

標籤：javascript 反应 反应钩子 动态形式

上一篇：如何使用js將字串拆分為陣列

下一篇：關鍵字的Javascript字串模板決議