Vite (วีท)

Env Variables and Modes

Env Variables

Vite exposes env variables on the special import.meta.env object. Some built-in variables are available in all cases:

  • import.meta.env.MODE: {string} the mode the app is running in.

  • import.meta.env.BASE_URL: {string} the base url the app is being served from. This is determined by the base config option.

  • import.meta.env.PROD: {boolean} whether the app is running in production.

  • import.meta.env.DEV: {boolean} whether the app is running in development (always the opposite of import.meta.env.PROD)

Production Replacement

During production, these env variables are statically replaced. It is therefore necessary to always reference them using the full static string. For example, dynamic key access like import.meta.env[key] will not work.

It will also replace these strings appearing in JavaScript strings and Vue templates. This should be a rare case, but it can be unintended. You may see errors like Missing Semicolon or Unexpected token in this case, for example when "process.env.NODE_ENV: " is transformed to ""development": ". There are ways to work around this behavior:

  • For JavaScript strings, you can break the string up with a unicode zero-width space, e.g. 'import.meta\u200b.env.MODE'.

  • For Vue templates or other HTML that gets compiled into JavaScript strings, you can use the <wbr> tag, e.g. import.meta.<wbr>env.MODE.

.env Files

Vite uses dotenv to load additional environment variables from the following files in your environment directory:

.env                # loaded in all cases
.env.local          # loaded in all cases, ignored by git
.env.[mode]         # only loaded in specified mode
.env.[mode].local   # only loaded in specified mode, ignored by git

Env Loading Priorities

An env file for a specific mode (e.g. .env.production) will take higher priority than a generic one (e.g. .env).

In addition, environment variables that already exist when Vite is executed have the highest priority and will not be overwritten by .env files.

.env files are loaded at the start of Vite. Restart the server after making changes.

Loaded env variables are also exposed to your client source code via import.meta.env.

To prevent accidentally leaking env variables to the client, only variables prefixed with VITE_ are exposed to your Vite-processed code. e.g. the following file:

DB_PASSWORD=foobar
VITE_SOME_KEY=123

Only VITE_SOME_KEY will be exposed as import.meta.env.VITE_SOME_KEY to your client source code, but DB_PASSWORD will not.

If you want to customize env variables prefix, see envPrefix option.

SECURITY NOTES

  • .env.*.local files are local-only and can contain sensitive variables. You should add .local to your .gitignore to avoid them being checked into git.

  • Since any variables exposed to your Vite source code will end up in your client bundle, VITE_* variables should not contain any sensitive information.

IntelliSense for TypeScript

By default, Vite provides type definition for import.meta.env in vite/client.d.ts. While you can define more custom env variables in .env.[mode] files, you may want to get TypeScript IntelliSense for user-defined env variables which prefixed with VITE_.

To achieve, you can create an env.d.ts in src directory, then augment ImportMetaEnv like this:

/// <reference types="vite/client" />

interface ImportMetaEnv {
  readonly VITE_APP_TITLE: string
  // more env variables...
}

interface ImportMeta {
  readonly env: ImportMetaEnv
}

Modes

By default, the dev server (dev command) runs in development mode and the build command run in production mode.

This means when running vite build, it will load the env variables from .env.production if there is one:

# .env.production
VITE_APP_TITLE=My App

In your app, you can render the title using import.meta.env.VITE_APP_TITLE.

However, it is important to understand that mode is a wider concept than just development vs. production. A typical example is you may want to have a "staging" mode where it should have production-like behavior, but with slightly different env variables from production.

You can overwrite the default mode used for a command by passing the --mode option flag. For example, if you want to build your app for our hypothetical staging mode:

vite build --mode staging

And to get the behavior we want, we need a .env.staging file:

# .env.staging
NODE_ENV=production
VITE_APP_TITLE=My App (staging)

Now your staging app should have production-like behavior, but display a different title from production.