second step in pkce flow to get an access token from our auth code

pkce_token_step.js

const PKCEAuthCodeSecondStep = ( code ) => {
  let oidcURL = `${process.env.OIDC_IDP_URL}/token`;

  let params = qs.stringify( {
    grant_type: "authorization_code",
    redirect_uri: "http://localhost/login_oidc",
    client_id: process.env.OIDC_CLIENT_ID,
    code_verifier: localStorage.getItem( 'code_verifier' ),
    code
  } );

  localStorage.removeItem( 'code_verifier' );
  return axios.post( oidcURL, params,
    { headers: { 'Content-Type': 'application/x-www-form-urlencoded' } }
  ).then( res => {
    localStorage.setItem( 'access_token', res.data.access_token );
    return res.data
  } );
}