Custom Templates

Meta Env Typed allows you to customize the generated type definition files using your own templates.

Why Custom Templates?

While the default templates work well for most projects, you might want to:

• Add additional type information
• Include custom documentation
• Format the output differently
• Support special use cases

Creating a Custom Template

To use a custom template, create a file with your desired template and reference it in your configuration.

Template Format

Templates use a simple placeholder syntax:

• {{envVars}} - Will be replaced with the environment variable declarations
• {{importMeta}} - Will be replaced with the ImportMeta interface declaration

Example Custom Template

my-template.ts

/**
 * Custom environment variables template
 * Generated on: {{date}}
 */

{ { envVars; } }

{ { importMeta; } }

// Add any additional custom types here
declare global {
  namespace NodeJS {
    interface ProcessEnv extends ImportMetaEnv {}
  }
}

Using Your Custom Template

Configure your build tool to use your custom template:

vite.config.ts

import path from 'node:path';
import envTyped from 'meta-env-typed/vite';
import { defineConfig } from 'vite';

export default defineConfig({
  plugins: [
    envTyped({
      template: path.resolve(__dirname, './my-template.ts')
    })
  ]
});

Available Template Variables

Variable	Description
{{envVars}}	The environment variable interface declarations
{{importMeta}}	The ImportMeta interface declaration
{{date}}	The current date and time
{{prefix}}	The environment variable prefix (e.g., "VITE_")

Advanced Template Customization

For more advanced customization, you can provide a template function instead of a file path:

import envTyped from 'meta-env-typed/vite';
import { defineConfig } from 'vite';

export default defineConfig({
  plugins: [
    envTyped({
      template: (envVars, importMeta) => `
        // Custom template function
        // Generated on: ${new Date().toISOString()}

        ${envVars}

        ${importMeta}

        // Additional custom types
        declare global {
          namespace NodeJS {
            interface ProcessEnv extends ImportMetaEnv {}
          }
        }
      `
    })
  ]
});

This approach gives you full control over the generated output.