Pass Rails ENV to Front End

22 Feb 2018

Sometimes you need ENV values from rails in your front end. Maybe API_BASE_URL or a MAPBOX_TOKEN. Here is a simple approach, make an env.js.erb file in assets and set it up as follows.

var ENV = {
  BASE_URL: '<%= ENV['BASE_URL'] %>',

Because JS and Ruby are so similar you can access the values anywhere from the front end the same way you do in Ruby.

var token = ENV['MAPBOX_TOKEN'];

Note that you need to be careful what values you make available to your front end and make sure you only provide values that can be publicized.

Improvements, bugs, typos? Contribute on GitHub ❤️