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

• Create directory in /packages/my-package/

• Add package.js with proper dependencies

• Implement functionality with proper exports

• Add tests in *-tests.js

• 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