React Pro - Real World App - Ch6. 14 Form Prevent Default

// pages/checkout/CheckoutPage.tsx

import clsx from 'clsx';
import { selectTotalCartCost, useCart } from '@/services/cart';
import { ChangeEvent, useState } from 'react';

export const EMAIL_REGEX = /^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;

export function CheckoutPage() {
  const [user, setUser] = useState({ name: '', email: ''});
  const [dirty, setDirty] = useState(false);

  const totalCartCost = useCart(selectTotalCartCost);

  function changeHandler(e: ChangeEvent<HTMLInputElement>) {
    const name = e.currentTarget.name;
    const value = e.currentTarget.value;
    setUser(state => ({ ...state, [name]: value }));
    setDirty(true);
  }


  function sendOrder(e: React.FormEvent<HTMLFormElement>) {
    e.preventDefault()
    console.log(user)
  }


  const isNameValid = user.name.length;
  const isEmailValid = user.email.match(EMAIL_REGEX);
  const isValid = isNameValid && isEmailValid;

  return (
    <div className="max-w-sm mx-auto">
      <h1 className="title">CHECKOUT</h1>

      <div className="text-xl my-3 border-b">€ {totalCartCost}</div>

      <form className="flex flex-col gap-3" onSubmit={sendOrder}>
        Your name:
        <input
          type="text" placeholder="your name"
          name="name"
          value={user.name}
          onChange={changeHandler}
          className={clsx({ 'error': !isNameValid && dirty})}
        />

        Your email
        <input
          type="email" placeholder="Your email"
          name="email"
          value={user.email}
          onChange={changeHandler}
          className={clsx({ 'error': !isEmailValid && dirty })}
        />

        <button type="submit" className="btn primary" disabled={!isValid}>
          CONFIRM ORDER
        </button>
      </form>

      <pre>{JSON.stringify(user, null, 2)}</pre>
    </div>
  )
}