til/javascript/load-and-use-env-var-in-node-script.md

Load And Use Env Var In Node Script

The node scripts defined under scripts in a package.json file can be used to do all sorts of handy development tasks for a project.

There are times where those scripts would be even more useful if they had access to environment variables specified in the project's .env files.

With the help of dotenv-cli and cross-var, we can load in and reference the project's env vars.

As an example, let's say our .env file has a DATABASE_URL:

DATABASE_URL="postgresql://postgres:postgres@localhost:5432/postgres"

We can create a node script in package.json that accesses that value like so:

{
  "scripts": {
    "db:url": "dotenv cross-var -- echo \"%DATABASE_URL%\""
  }
}

Running that command will echo out the value:

❯ npm run db:url

> db:url
> dotenv cross-var -- echo "%DATABASE_URL%"

postgresql://postgres:postgres@localhost:9876/postgres

You could do something more useful with that value like open a psql connection to that local database.

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