Answers for "how to use usestate hook"

usestate hook

import React, { useState } from 'react';

function Example() {
  // Declare a new state variable, which we'll call "count"  
  const [count, setCount] = useState(0);
  return (
    <div>
      <p>You clicked {count} times</p>
      <button onClick={() => setCount(count + 1)}>
        Click me
      </button>
    </div>
  );
}

state with react functions

class Example extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      count: 0
    };
  }

  render() {
    return (
      <div>
        <p>You clicked {this.state.count} times</p>
        <button onClick={() => this.setState({ count: this.state.count + 1 })}>
          Click me
        </button>
      </div>
    );
  }
}

useState hook example

function LoginForm() {
  const [form, setState] = useState({
    username: '',
    password: ''
  });

  const printValues = e => {
    e.preventDefault();
    console.log(form.username, form.password);
  };

  const updateField = e => {
    setState({
      ...form,
      [e.target.name]: e.target.value
    });
  };

  return (
    <form onSubmit={printValues}>
      <label>
        Username:
        <input
          value={form.username}
          name="username"
          onChange={updateField}
        />
      </label>
      <br />
      <label>
        Password:
        <input
          value={form.password}
          name="password"
          type="password"
          onChange={updateField}
        />
      </label>
      <br />
      <button>Submit</button>
    </form>
  );
}