conventions
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.
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- September 4, 2026 at 13:43
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- conventions
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- 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
```javascript
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:
```javascript
main.registerCommand({
name: 'my-command',
options: {
'option-name': { type: String, short: 'o' }
},
catalogRefresh: new catalog.Refresh.Never()
}, function(options) {
// Implementation
});
```
### WebApp Middleware Pattern
```javascript
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
```javascript
// 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
```javascript
// In package.js
api.use('tools-core');
// In implementation
import {
logProgress,
ensurePackageDependencies,
getMeteorAppDir,
spawnProcess
} from 'meteor/tools-core';
// Declare host-app dependencies. The shared engine handles auto-install versus
// manual instructions; do not gate it on meteor.autoInstallDeps yourself.
await ensurePackageDependencies({
packageId: 'my-compiler',
packageLabel: 'My Compiler',
dependencies: [
{ name: '@rspack/core', version: '1.7.1', semverCondition: 'gte', dev: true }
]
});
// 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
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