login_react_native.js

export const signIn = (email, password) => {
  return (dispatch, getState) => {
    return new Promise((resolve, reject) => {
      return fetch(`${BASE_URL}/auth/sign_in`, {
        method: 'POST',
        timeout: REQUEST_TIMEOUT,
        headers: {
          'Content-Type': 'application/json',
        },
        body: JSON.stringify({
          email,
          password
        }),
      })
      .then(handleFetchErrors)
      .then(res => res.json().then(json => ({
        headers: res.headers,
        status: res.status,
        json
      })))
      .then(({ headers, status, json }) => {
        const promises = getAvailableHeaders(headers)
        Promise.all(promises).then(credentials => {
          return resolve(true);
        })
      })
      .catch(error => {
        parseFetchError(error)
        .then(errorObject => reject(errorObject))
      })
    })
  }
}