fetch() 사용법

fetch('http://10.58.52.230:3008/auth/signin', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json;charset=utf-8' },
  body: JSON.stringify({
    email: isIdValue,
    password: isPwValue,
  }),
})
  .then(response => {
    console.log(response);
    if (response.status != 200) {
      throw new Error('error');
      alert('로그인 실패');
    }
    return response.json();
  })
  .catch(err => {
    console.log(err);
    alert('로그인 실패');
  })
  .then(data => {
    localStorage.setItem('token', data.accessToken);
    return navMain('/MainPmy');
  });