axios.interceptor.js

axiosInstance.interceptors.response.use(
  response => response,
  error => {
    const originalRequest = error.config;
    if (error.response.status === 401 && error.response.statusText === "Unauthorized"
        && error.response.data.code === "token_not_valid") {
      const refreshToken = localStorage.getItem('refresh_token');
      if (refreshToken) {
        const tokenParts = JSON.parse(atob(refreshToken.split('.')[1]));
        // exp date in token is expressed in seconds, while now() returns milliseconds:
        const now = Math.ceil(Date.now() / 1000);
        if (tokenParts.exp > now) {
          return axiosInstance
            .post('/token/refresh/', {refresh: refreshToken})
            .then((response) => {

              localStorage.setItem('access_token', response.data.access);
              localStorage.setItem('refresh_token', response.data.refresh);

              axiosInstance.defaults.headers['Authorization'] = "JWT " + response.data.access;
              originalRequest.headers['Authorization'] = "JWT " + response.data.access;

              return axiosInstance(originalRequest);
            })
            .catch(err => {
              console.log(err)
            });
        } else {
            console.log("Refresh token is expired", tokenParts.exp, now);
        }
      } else {
        console.log("no refresh token");
      }

    } // else error is different from 401
    return Promise.reject(error);
  }
);