import React from "react";
import ReactDOM from "react-dom";
import useForm from "react-hook-form";

const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));

function App() {
  const { register, handleSubmit, errors } = useForm();
  const onSubmit = async data => {
    await sleep(2000);
    if (data.username === "bill") {
      alert(JSON.stringify(data));
    } else {
      alert("There is error");
    }
  };

  console.log(errors);

  return (
    <div className="App">
      <form onSubmit={handleSubmit(onSubmit)}>
        <div>
          <label htmlFor="username">User Name</label>
          <input name="username" placeholder="Bill" ref={register} />
        </div>

        <div>
          <label htmlFor="lastName">Last Name</label>
          <input name="lastName" placeholder="Luo" ref={register} />
        </div>

        <div>
          <label htmlFor="email">Email</label>
          <input
            name="email"
            placeholder="bluebill1049@hotmail.com"
            type="text"
            ref={register}
          />
        </div>

        <div style={{ color: "red" }}>
          {Object.keys(errors).length > 0 &&
          "There are errors, check your console."}
        </div>
        <button type="submit">Submit</button>
      </form>
    </div>
  );
}

const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);