How to Use .env Environment Variables in Vue

When we make a Node.js application, it's pretty typical that we also create a .env file that stores all of our environment variables. This file is typically private and can be used to store things like API keys, URLs, and other things that are specific to one environment.

Vue.js also lets us use .env variables, but it works slightly differently. So let's look at how to use .env variables in Vue.

Using .env variables in Vue

In Vue CLI, .env works pretty much as you'd expect. In your base directory, you can make a .env file like so:

Typical Vue Folder Structure with .env

|- public <-- Our public folder
|- src <-- Our src folder 
|- .env <-- Our .env file

In our .env file itself, we can start to define our .env variables. Vue CLI actually supports a few different names for the .env file:

.env                # loaded on all projects
.env.local          # loaded on all projects, but ignored by git by default
.env.[mode]         # only loaded in a specific mode
.env.[mode].local   # only loaded in a specific mode, but ignored by git by default

You might notice that we have this concept of mode above. The mode, in Vue CLI, is the environment you are using. The easiest way to build your Vue application in a specific mode is to run the vue-cli-service like this:

vue-cli-service build --mode development

If we ran this command, then .env, .env.local, .env.development, .env.development.local would be loaded by Vue - assuming they were available. This means we can have a custom .env file depending on the environment we configure our code in.

As well as this, it's good to know that Vue CLI has 3 standard ways of firing test, development, and production:

vue-cli-service serve     # mode will be 'development'
vue-cli-service test:unit # mode will be 'test'
vue-cli-service build     # mode will be 'production

Using your .env file

Now that it's clear how to make .env files, and where they go, let's look at the content of them. The difference between a normal, Node.js .env and a Vue CLI is that Vue will only load variables that start with VUE_APP_.

So if our .env contents look like this:

VUE_APP_API_KEY = 123-123-123-123
VUE_APP_API_BASE = https://some-app.fjolt.com/api/
topSecretCode = someSecretName

Then only VUE_APP_API_KEY and VUE_APP_API_BASE will be available to use in our Vue application. All other variables will be ignored. As well as any variable starting with VUE_APP_, you also have access to:

• NODE_ENV - the environment depending on which --mode is used.
• BASE_URL - the URL configured in your publicPath variable in vue.config.js.

Using your .env variables in your Vue application

Now that we know how to create the contents of our .env files, using them in our files is super easy. You can access any valid variable from your .env file via process.env. So if you wanted to use VUE_APP_API_KEY in your code, you could write this in Javascript:

console.log(process.env.VUE_APP_API_KEY)

Conclusion

.env files are a great way to store data about your application by the environment, and they're pretty straightforward with a tool like Vue CLI. I hope you've enjoyed this guide to .env in Vue.

Also published here.