conventions

name	conventions
description	Use when writing new packages, adding CLI commands, creating build plugins, or following Meteor code patterns. Covers package.js structure, file naming, and common code patterns.

Code Conventions

Package structure, file naming, and code patterns for the Meteor codebase.

Package Structure

Every Meteor package follows this structure:

packages/my-package/
├── package.js          # Package manifest (name, version, dependencies, exports)
├── my-package.js       # Main implementation (or split by concern)
├── my-package-server.js # Server-only code (optional)
├── my-package-client.js # Client-only code (optional)
├── my-package-tests.js  # Tests (loaded via api.addFiles in test mode)
└── README.md           # Documentation (optional)

Package.js Anatomy

Package.describe({
  name: 'my-package',
  version: '1.0.0',
  summary: 'Brief description',
  git: 'https://github.com/meteor/meteor.git',
  documentation: 'README.md'
});

Package.onUse(function(api) {
  api.versionsFrom(['3.0']);  // Minimum Meteor version

  api.use([
    'ecmascript',            // ES2015+ support
    'mongo',                 // MongoDB integration
    'tracker'                // Reactivity (client)
  ]);

  api.use('accounts-base', { weak: true }); // Optional dependency

  api.mainModule('my-package-server.js', 'server');
  api.mainModule('my-package-client.js', 'client');

  api.export('MyPackage');   // Global export
});

Package.onTest(function(api) {
  api.use(['tinytest', 'my-package']);
  api.addFiles('my-package-tests.js');
});

Npm.depends({
  'lodash': '4.17.21'        // npm dependencies
});

File Naming Conventions

Pattern	Purpose
*-server.js	Server-only code
*-client.js	Client-only code
*-common.js	Shared code
*-tests.js	Test files
*.d.ts	TypeScript declarations

Common Patterns

Adding a New Core Package

1. Create directory in /packages/my-package/
2. Add package.js with proper dependencies
3. Implement functionality with proper exports
4. Add tests in *-tests.js
5. Update version numbers if needed

Modifying Build System

Key files to understand:

• /tools/isobuild/bundler.js - High-level bundling
• /tools/isobuild/compiler.js - Package compilation
• /tools/project-context.js - Dependency resolution
• /tools/cli/commands.js - CLI command handlers

Adding CLI Commands

Edit /tools/cli/commands.js or create new command file:

main.registerCommand({
  name: 'my-command',
  options: {
    'option-name': { type: String, short: 'o' }
  },
  catalogRefresh: new catalog.Refresh.Never()
}, function(options) {
  // Implementation
});

WebApp Middleware Pattern

import { WebApp } from 'meteor/webapp';

// Add middleware before Meteor's default handlers
WebApp.rawConnectHandlers.use('/api', (req, res, next) => {
  // Runs before authentication
  next();
});

// Add middleware after authentication
WebApp.connectHandlers.use('/api', (req, res, next) => {
  // req.userId available if authenticated
  next();
});

Build Plugin Pattern

// In package.js
Package.registerBuildPlugin({
  name: 'compile-my-files',
  use: ['ecmascript', 'caching-compiler'],
  sources: ['plugin.js'],
  npmDependencies: { 'my-compiler': '1.0.0' }
});

// In plugin.js
Plugin.registerCompiler({
  extensions: ['myext'],
  archMatching: 'web'
}, () => new MyCompiler());

class MyCompiler extends CachingCompiler {
  getCacheKey(inputFile) {
    return inputFile.getSourceHash();
  }

  compileOneFile(inputFile) {
    const source = inputFile.getContentsAsString();
    const compiled = transform(source);
    inputFile.addJavaScript({
      data: compiled,
      path: inputFile.getPathInPackage() + '.js'
    });
  }
}

Using tools-core in Packages

// In package.js
api.use('tools-core');

// In implementation
import {
  logProgress,
  checkNpmDependencyExists,
  getMeteorAppConfig,
  spawnProcess
} from 'meteor/tools-core';

// Check and install dependencies
if (!checkNpmDependencyExists('@rspack/core')) {
  installNpmDependency(['@rspack/core@^1.7.1']);
}

// Spawn external process
const proc = spawnProcess('npx', ['rspack', 'build'], {
  cwd: getMeteorAppDir(),
  onStdout: (data) => logProgress(data)
});

Version Patterns

Meteor uses X.Y.Z-rcN.M versioning where:

• X.Y.Z - Semantic version
• rcN - Release candidate number
• M - Package-specific revision