What's the solution to form validation issues in React JSX?-PHP Chinese Network Q&A

I'm trying to make a validation form in React but I'm having a lot of problems since I added saving user registration data.

import React, { useState } from "react";
import "./registerstyle.css";
import EyeIcon from "./EyeIcon.png";
import EyeIconHide from "./EyeIconHide.png";
import { signup } from "../../api/client";

function RegisterPage() {
  const [showPassword, setShowPassword] = useState(false);
  const [passwordVisible, setPasswordVisible] = useState(false);
  const [showConfirmPassword, setShowConfirmPassword] = useState(false);
  const [confirmPasswordVisible, setConfirmPasswordVisible] = useState(false);
  const [nameEmpty, setNameEmpty] = useState(false);
  const [confirmPasswordEmpty, setconfirmPasswordEmpty] = useState(false);
  const [emailEmpty, setEmailEmpty] = useState(false);
  const [passwordEmpty, setPasswordEmpty] = useState(false);
  const [newsletter, setNewsletter] = useState(false); // Aggiunto lo stato per la checkbox

  const [name, setName] = useState(null);
  const [email, setEmail] = useState(null);
  const [password, setPassword] = useState(null);
  const [cpass, setCpass] = useState(null);
  const user = { name: name, email: email, password: password, cpass: cpass };



  const handleShowPassword = () => {
    setShowPassword(!showPassword);
    setPasswordVisible(!passwordVisible);
  };

  const handleShowConfirmPassword = () => {
    setShowConfirmPassword(!showConfirmPassword);
    setConfirmPasswordVisible(!confirmPasswordVisible);
  };

  const handleFormSubmit = (e) => {
    e.preventDefault();

    // Verifica se i campi email e password sono vuoti
    if (!e.target.email.value) {
      setEmailEmpty(true);
      console.log("email True");
    } else {
      setEmailEmpty(false);
      console.log("email False");
    }

    if (!e.target.name.value) {
      setNameEmpty(true);
    } else {
      setNameEmpty(false);
    }

    if (!e.target.password.value) {
      setPasswordEmpty(true);
    } else {
      setPasswordEmpty(false);
    }

    if (!e.target.confirmPassword.value) {
      setconfirmPasswordEmpty(true);
    } else {
      setconfirmPasswordEmpty(false);
    }
  };

  const handleNewsletterChange = (e) => {
    setNewsletter(e.target.checked);
  }; // Funzione per gestire il cambiamento di stato della checkbox

  const passwordInputClass = passwordVisible ? "passwordVisible" : "";
  const confirmPasswordInputClass = confirmPasswordVisible ? "confirmPasswordVisible" : "";

  return (
    <div className="backgroundRegister">
      <div className="titleRegister" />
      <div className="breakRegister" />
      <div className="contlogRegister" />
      <div className="signIn" />
      <form className="formRegister" onSubmit={handleFormSubmit}>
        <label>
          {/* NAME */}
          <input type="text" name="name" placeholder="Name" onChange={(e) => { setName(e.target.value) }} required/>
        </label>
        {nameEmpty && (
          <div>
            <div className="alertCircleName" />
            <div className="FillThisName" />
            <div className="RedRectangleName" />
            <div className="nameError" />
          </div>
        )}
        <br />
        <label>
          {/* EMAIL */}
          <input type="email" name="email" placeholder="Email" onChange={(e) => { setEmail(e.target.value) }} required/>
        </label>
        {emailEmpty && (
          <div>
            <div className="alertCircleEmailRegister" />
            <div className="FillThisEmailRegister" />
            <div className="RedRectangleEmailRegister" />
            <div className="emailErrorRegister" />
          </div>
        )}
        <br />
        <label>
          {/* PASSWORD*/}
          <input
            type={showPassword ? "text" : "password"}
            name="password"
            placeholder="Password"
            className={passwordInputClass}
            onChange={(e) => { setPassword(e.target.value) }}
          />
          <img
            src={passwordVisible ? EyeIconHide : EyeIcon}
            alt="eye-icon"
            className="eyeIconRegister1"
            onClick={() => {
              handleShowPassword();
            }}
          />
        </label>
        {passwordEmpty && (
          <div>
            <div className="alertCirclePasswordRegister" />
            <div className="FillThisPasswordRegister" />
            <div className="RedRectanglePasswordRegister" />
            <div className="passwordErrorRegister" />
          </div>
        )}
        <br />
        <label>
          {/* CONFIRM PASSWORD */}
          <input
            type={showConfirmPassword ? "text" : "password"}
            name="confirmPassword"
            placeholder="Confirm Password"
            className={confirmPasswordInputClass}
            onChange={(e) => { setCpass(e.target.value) }}
          />
          <img
            src={confirmPasswordVisible ? EyeIconHide : EyeIcon}
            alt="eye-icon"
            className="eyeIconRegister2"
            onClick={() => {
              handleShowConfirmPassword();
            }}
          />
        </label>
        {confirmPasswordEmpty && (
          <div>
            <div className="alertCircleConfirmPassword" />
            <div className="FillThisConfirmPassword" />
            <div className="RedRectangleConfirmPassword" />
            <div className="confirmPasswordError" />
          </div>
        )}
        <br />
        <label> {/* NEWSLETTER */}
          <input type="checkbox" name="newsletter" checked={newsletter} onChange={handleNewsletterChange} />
        </label>
        <span className="newsletter">Send me newsletters, tricks and updates. </span>
        <br />
        <input type="submit" value="SIGN IN" className="signInButton" onClick={(e) => {
          e.preventDefault();
          signup(user);
          handleFormSubmit(e);
        }}/>
      </form>
      <div className="registerSign">
        Already have an account? <a href="" className="colorRegister">Login now</a>
      </div>
    </div>

  );
}

export default RegisterPage;

This is the registration code:

import axios from "axios";

// const client = axios.create({
//   baseURL: "http://localhost:9000", // o l'endpoint del vostro backend
//   headers: {
//     "Content-Type": "application/json",
//     //     "Authorization": "Bearer " + localStorage.getItem("token")
//   }
// });

// export default client;


async function signup(user) {
  const newUser = JSON.stringify(user);
  console.log("sono dentro la funzione");

  try {
    return await axios.post("http://localhost:3000/signup", newUser);
  } catch (err) {
    if (err.response) {
      return err.response.data;
    } else {
      console.log("Errore:", err.message);
    }
  }
};

async function login(user) {
  const newUser = JSON.stringify(user);
  console.log("sono dentro");

  try {
    return await axios.post("http://localhost:3000/login", newUser);
    //return await axios.post("http://localhost:3000/login",)
  } catch (err) {
    if (err.response) {
      return err.response.data;
    } else {
      console.log("Errore:", err.message);
    }
  }
};

async function loginOld(credentials) {
  const loginData = JSON.stringify(credentials);
  await axios.post("http://localhost:3000/login", loginData);
};

export { signup, login };

What I expected to happen, when the fields were left blank when you clicked the button, was that they would pop up from the image I created to circle the fields that were left blank. Sometimes it gives errors like:

TypeError: Cannot read properties of undefined (reading 'value')
    at handleFormSubmit (http://localhost:3000/main.7b4752724621de0f0bc6.hot-update.js:66:25)
    at onClick (http://localhost:3000/main.7b4752724621de0f0bc6.hot-update.js:387:11)
    at HTMLUnknownElement.callCallback (http://localhost:3000/static/js/bundle.js:14655:18)
    at Object.invokeGuardedCallbackDev (http://localhost:3000/static/js/bundle.js:14699:20)
    at invokeGuardedCallback (http://localhost:3000/static/js/bundle.js:14756:35)
    at invokeGuardedCallbackAndCatchFirstError (http://localhost:3000/static/js/bundle.js:14770:29)
    at executeDispatch (http://localhost:3000/static/js/bundle.js:18914:7)
    at processDispatchQueueItemsInOrder (http://localhost:3000/static/js/bundle.js:18940:11)
    at processDispatchQueue (http://localhost:3000/static/js/bundle.js:18951:9)
    at dispatchEventsForPlugins (http://localhost:3000/static/js/bundle.js:18960:7)```

I'm desperate and don't really know where to put my hands.