Fixing process.env Undefined in Vite

Understanding the Issue: process.env Undefined in Vite

When using Vite as a bundler for your Vue.js or JavaScript projects, you may encounter the following error while working with libraries like Tesseract.js:

Cannot read properties of undefined (reading 'TESS_ENV')

This typically happens because Vite replaces process.env with import.meta.env. Unlike Webpack, Vite uses import.meta.env for environmental variables. If your library relies on process.env, it can lead to such errors.

Solution: How to Fix process.env in Vite

To resolve this issue, follow the steps below:

1. Use import.meta.env Instead of process.env

Vite requires all environment variables to be prefixed with VITE_. For example, declare your variable in an .env file:

VITE_TESS_ENV=development

In your code, use import.meta.env to access the variable:

const isDevelopment = import.meta.env.VITE_TESS_ENV === 'development'

2. Define process.env in vite.config.js

If you are using a library that directly references process.env (e.g., Tesseract.js), you can define it in your Vite configuration file. Add the following code to your vite.config.js:

import { defineConfig } from 'vite'

export default defineConfig({
  define: {
    'process.env.TESS_ENV': JSON.stringify('development'),
  },
})

This will make process.env.TESS_ENV available in your application.

3. Modify the Library (If Necessary)

If the library's default behavior is incompatible with Vite, you can modify the source code within node_modules. Locate the problematic file (e.g., defaultOptions.js for Tesseract.js):

module.exports = {
  ...defaultOptions,
  workerPath:
    import.meta.env.MODE === 'development'
      ? resolveURL(`/dist/worker.dev.js?nocache=${Math.random().toString(36).slice(3)}`)
      : `https://unpkg.com/tesseract.js@v${version}/dist/worker.min.js`,
}

Note: Directly modifying files in node_modules is not recommended for long-term solutions. Instead, fork the library or submit a pull request to address the issue.

Best Practices for Using Environment Variables in Vite

1. Always Prefix Variables with VITE_: Variables in .env must start with VITE_. For example:

   VITE_API_URL=https://api.example.com
   

2. Access Variables with import.meta.env: Use the following syntax:

   const apiUrl = import.meta.env.VITE_API_URL
   console.log(apiUrl)
   

3. Define Variables in vite.config.js When Necessary: If you need compatibility with older libraries:

   export default defineConfig({
     define: {
       'process.env.MY_VAR': JSON.stringify('myValue'),
     },
   })
   

Example Code

.env File

VITE_TESS_ENV=development

vite.config.js

import { defineConfig } from 'vite'

export default defineConfig({
  define: {
    'process.env.TESS_ENV': JSON.stringify(process.env.VITE_TESS_ENV),
  },
})

Application Code

console.log(import.meta.env.VITE_TESS_ENV)

FAQs

1. Why is process.env undefined in Vite?

Vite does not use process.env for environment variables. Instead, it uses import.meta.env to access variables declared in .env files.

2. How do I define a custom environment variable in Vite?

Add your variable to the .env file with a VITE_ prefix. For example:

VITE_CUSTOM_VAR=myValue

Access it in your code using import.meta.env.VITE_CUSTOM_VAR.

3. Can I use process.env directly in Vite projects?

Yes, but you need to define it explicitly in the Vite configuration file using the define option:

export default defineConfig({
  define: {
    'process.env.MY_VAR': JSON.stringify('value'),
  },
})