Access static variable from another class in React-Native app?

I think you also forgot the this keyword for returning the static "currentUser" field:

class User {
  constructor() {}

  static currentUser = {
    uname: 'xxx',
    firstname: 'first',
    lastname: 'last'
  };

  static getCurrentUser() {
    return this.currentUser;
  }
}

console.log(User.getCurrentUser());

You are mixing import / export styles. You should either change your import to

var User = require('./User').default

or

import User from './User'

Or change your export:

module.exports = User