React 设计模式~容器组件/不受控制的受控组件~

import react from "react";

export const uncontrolledform = () => {
  const nameinputref = react.createref();
  const ageinputref = react.createref();

  console.log("renedering");

  const submitform = (e) => {
    console.log(nameinputref.current.value);
    console.log(ageinputref.current.value);

    e.preventdefault();
  };

  return (
    <form onsubmit={submitform}>
      <input name="name" type="text" placeholder="name" ref={nameinputref} />
      <input name="age" type="number" placeholder="age" ref={ageinputref} />
      <input type="submit" value="submit" />
    </form>
  );
};

import React, { useEffect, useState } from "react";

export const ControlledForm = () => {
  const [errorMessage, setErrorMessage] = useState("");
  const [name, setName] = useState("");
  const [age, setAge] = useState();

  useEffect(() => {
    if (name.length < 1) {
      setErrorMessage("name can not be empty");
    } else {
      setErrorMessage("");
    }
  }, [name]);

  return (
    <form>
      {errorMessage&& <p>{errorMessage}</p>}
      <input
        type="text"
        name="name"
        placeholder="Name"
        value={name}
        onChange={(e) => setName(e.target.value)}
      />
      <input
        type="number"
        name="age"
        placeholder="Age"
        value={age}
        onChange={(e) => setAge(e.target.value)}
      />
      <button>Submit</button>
    </form>
  );
};