Bundling with build tools

Temelj packages are distributed as ES modules optimized for modern bundlers. This guide covers configuration for popular build tools and optimization strategies.

Package structure

Each Temelj package follows a consistent structure:

Package layout

@temelj/result/
├── dist/
│   ├── mod.mjs          # ES module entry point
│   └── mod.d.mts        # TypeScript declarations
├── package.json         # Package metadata
└── README.md

The package.json exports field provides the entry point:

Package exports

{
  "name": "@temelj/result",
  "type": "module",
  "main": "./dist/mod.mjs",
  "types": "./dist/mod.d.mts",
  "exports": {
    ".": {
      "types": "./dist/mod.d.mts",
      "import": "./dist/mod.mjs"
    }
  }
}

All Temelj packages use the .mjs extension and "type": "module" to ensure they’re treated as ES modules by all tools.

Vite

Vite works with Temelj packages out of the box with minimal configuration.

Basic configuration

vite.config.ts

import { defineConfig } from 'vite';
import { resolve } from 'path';

export default defineConfig({
  build: {
    target: 'es2022',
    minify: 'esbuild',
    sourcemap: true,
    rollupOptions: {
      output: {
        manualChunks: {
          // Separate Temelj utilities into their own chunk
          'temelj-core': [
            '@temelj/result',
            '@temelj/value',
            '@temelj/string'
          ],
          'temelj-async': ['@temelj/async']
        }
      }
    }
  },
  optimizeDeps: {
    include: [
      '@temelj/result',
      '@temelj/async',
      '@temelj/value',
      '@temelj/string'
    ]
  }
});

Library mode

When building a library that depends on Temelj:

vite.config.ts (library)

import { defineConfig } from 'vite';
import { resolve } from 'path';

export default defineConfig({
  build: {
    lib: {
      entry: resolve(__dirname, 'src/index.ts'),
      name: 'MyLibrary',
      formats: ['es'],
      fileName: 'index'
    },
    rollupOptions: {
      // Externalize Temelj packages
      external: [
        '@temelj/result',
        '@temelj/async',
        '@temelj/value',
        '@temelj/string',
        '@temelj/iterator',
        '@temelj/math',
        '@temelj/request',
        '@temelj/id',
        '@temelj/color'
      ]
    }
  }
});

Externalize Temelj packages in library mode to avoid bundling them twice when consumers install both your library and Temelj.

Webpack

Configure Webpack 5 to handle ES modules correctly.

webpack.config.js

import path from 'path';
import { fileURLToPath } from 'url';

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);

export default {
  entry: './src/index.ts',
  output: {
    path: path.resolve(__dirname, 'dist'),
    filename: '[name].[contenthash].js',
    module: true,
    chunkFormat: 'module'
  },
  experiments: {
    outputModule: true
  },
  module: {
    rules: [
      {
        test: /\.ts$/,
        use: 'ts-loader',
        exclude: /node_modules/
      }
    ]
  },
  resolve: {
    extensions: ['.ts', '.js', '.mjs'],
    extensionAlias: {
      '.js': ['.js', '.ts'],
      '.mjs': ['.mjs', '.mts']
    }
  },
  optimization: {
    moduleIds: 'deterministic',
    runtimeChunk: 'single',
    splitChunks: {
      cacheGroups: {
        temelj: {
          test: /[\\/]node_modules[\\/]@temelj[\\/]/,
          name: 'temelj',
          chunks: 'all',
          priority: 10
        },
        vendor: {
          test: /[\\/]node_modules[\\/]/,
          name: 'vendors',
          chunks: 'all'
        }
      }
    }
  }
};

TypeScript with Webpack

tsconfig.json

{
  "compilerOptions": {
    "target": "ES2022",
    "module": "ESNext",
    "moduleResolution": "bundler",
    "esModuleInterop": true,
    "resolveJsonModule": true,
    "isolatedModules": true,
    "jsx": "react-jsx"
  }
}

esbuild

Use esbuild for fast builds with Temelj packages.

build.js

import * as esbuild from 'esbuild';

await esbuild.build({
  entryPoints: ['src/index.ts'],
  bundle: true,
  outfile: 'dist/bundle.js',
  format: 'esm',
  target: 'es2022',
  platform: 'browser',
  minify: true,
  sourcemap: true,
  splitting: true,
  outdir: 'dist',
  outExtension: { '.js': '.mjs' },
  external: [
    // Optionally externalize for library builds
    // '@temelj/*'
  ],
  treeShaking: true,
  metafile: true
});

{
  "scripts": {
    "build": "node build.js",
    "build:watch": "node build.js --watch",
    "build:analyze": "node build.js --analyze"
  }
}

Rollup

Rollup configuration for Temelj packages.

rollup.config.js

import typescript from '@rollup/plugin-typescript';
import resolve from '@rollup/plugin-node-resolve';
import commonjs from '@rollup/plugin-commonjs';
import terser from '@rollup/plugin-terser';

export default {
  input: 'src/index.ts',
  output: [
    {
      file: 'dist/index.mjs',
      format: 'es',
      sourcemap: true
    },
    {
      file: 'dist/index.min.mjs',
      format: 'es',
      sourcemap: true,
      plugins: [terser()]
    }
  ],
  plugins: [
    resolve({
      extensions: ['.ts', '.js', '.mjs']
    }),
    commonjs(),
    typescript({
      tsconfig: './tsconfig.json',
      declaration: true,
      declarationDir: 'dist',
      rootDir: 'src'
    })
  ],
  external: [
    // For library builds, externalize Temelj
    /^@temelj\//
  ]
};

Turborepo (monorepo builds)

Temelj itself uses Turbo for its monorepo. Use this configuration as a reference.

turbo.json

{
  "$schema": "https://turborepo.com/schema.json",
  "tasks": {
    "build": {
      "dependsOn": ["^build"],
      "inputs": ["$TURBO_DEFAULT$", ".env*"],
      "outputs": ["dist/**"]
    },
    "dev": {
      "dependsOn": ["^build"],
      "cache": false,
      "persistent": true
    },
    "typecheck": {
      "dependsOn": ["^build"]
    },
    "test": {
      "dependsOn": ["^build"],
      "outputs": ["coverage/**"]
    }
  }
}

Using tsdown (Temelj's build tool)

Temelj packages use tsdown for builds:

package.json

{
  "scripts": {
    "build": "tsdown",
    "clean": "shx rm -rf dist"
  },
  "devDependencies": {
    "tsdown": "^0.20.3",
    "shx": "^0.4.0"
  }
}

tsdown automatically generates optimized .mjs and .d.mts files from TypeScript source with zero configuration.

Bundle size optimization

Temelj packages are already optimized, but you can further reduce bundle size.

Tree shaking

All Temelj packages support tree shaking. Import only what you need:

Optimized imports

// ✓ Good - only imports what you use
import { ok, err } from '@temelj/result';
import { retry } from '@temelj/async';

// ✗ Avoid - imports everything
import * as Result from '@temelj/result';
import * as Async from '@temelj/async';

Code splitting

Split Temelj utilities across chunks for better caching:

Identify shared utilities

Determine which Temelj packages are used across multiple routes or components.

Create dedicated chunks

Configure your bundler to separate frequently-used utilities:

Vite example

export default defineConfig({
  build: {
    rollupOptions: {
      output: {
        manualChunks(id) {
          if (id.includes('@temelj/result') || id.includes('@temelj/value')) {
            return 'utils-core';
          }
          if (id.includes('@temelj/async')) {
            return 'utils-async';
          }
        }
      }
    }
  }
});

Measure impact

Use bundle analysis tools to verify size improvements:

npx vite-bundle-visualizer

Dependency analysis

Check what Temelj packages bring in:

Bundle analysis

# Install analyzer
npm install -D webpack-bundle-analyzer

# For Webpack
npx webpack-bundle-analyzer dist/stats.json

# For Vite
npx vite-bundle-visualizer

# For esbuild (with metafile)
node -e "console.log(require('./meta.json'))"

Most Temelj packages have zero dependencies. Notable exceptions:

@temelj/value: uses deepmerge and react-fast-compare
@temelj/request: uses tough-cookie
@temelj/id: uses id128

Production optimization

Optimize for production deployments.

Environment-specific builds

vite.config.ts

import { defineConfig } from 'vite';

export default defineConfig(({ mode }) => ({
  build: {
    minify: mode === 'production' ? 'esbuild' : false,
    sourcemap: mode === 'development',
    target: 'es2022',
    rollupOptions: {
      output: {
        compact: mode === 'production',
        manualChunks: mode === 'production' ? {
          temelj: [
            '@temelj/result',
            '@temelj/async',
            '@temelj/value'
          ]
        } : undefined
      }
    }
  },
  define: {
    __DEV__: JSON.stringify(mode === 'development')
  }
}));

Compression

Enable compression for maximum size reduction:

vite.config.ts

import { defineConfig } from 'vite';
import compression from 'vite-plugin-compression';

export default defineConfig({
  plugins: [
    compression({
      algorithm: 'brotliCompress',
      ext: '.br',
      threshold: 1024
    }),
    compression({
      algorithm: 'gzip',
      ext: '.gz'
    })
  ]
});

Testing bundled output

Verify your bundle works correctly:

Bundle test

import { describe, it, expect } from 'vitest';
import { ok, isOk } from '@temelj/result';

describe('Bundled utilities', () => {
  it('imports Result utilities correctly', () => {
    const result = ok(42);
    expect(isOk(result)).toBe(true);
  });

  it('tree-shakes unused exports', async () => {
    // This test verifies that only imported functions are bundled
    const module = await import('@temelj/result');
    expect(module).toHaveProperty('ok');
    expect(module).toHaveProperty('err');
  });
});

Common bundling issues

If you encounter “Cannot find module” errors, ensure your bundler is configured to resolve .mjs extensions and ES modules correctly.

Module resolution errors

Check package.json type

Ensure your project uses ES modules:

{
  "type": "module"
}

Verify bundler configuration

Add .mjs to resolved extensions:

resolve: {
  extensions: ['.ts', '.tsx', '.js', '.jsx', '.mjs']
}

Update TypeScript config

Set proper module resolution:

{
  "compilerOptions": {
    "moduleResolution": "bundler"
  }
}

Dual package hazard

Avoid importing the same package as both ESM and CJS:

Avoid mixing formats

// ✗ Don't do this
import { ok } from '@temelj/result'; // ESM
const { err } = require('@temelj/result'); // CJS (not supported)

// ✓ Always use ESM imports
import { ok, err } from '@temelj/result';

Framework-specific guides

Next.js configuration

next.config.js

export default {
  experimental: {
    esmExternals: true
  },
  transpilePackages: [
    '@temelj/result',
    '@temelj/async',
    '@temelj/value',
    '@temelj/string'
  ],
  webpack: (config) => {
    config.resolve.extensionAlias = {
      '.js': ['.js', '.ts'],
      '.mjs': ['.mjs', '.mts']
    };
    return config;
  }
};

SvelteKit configuration

vite.config.js

import { sveltekit } from '@sveltejs/kit/vite';
import { defineConfig } from 'vite';

export default defineConfig({
  plugins: [sveltekit()],
  optimizeDeps: {
    include: [
      '@temelj/result',
      '@temelj/async',
      '@temelj/value'
    ]
  }
});

Astro configuration

astro.config.mjs

import { defineConfig } from 'astro/config';

export default defineConfig({
  vite: {
    optimizeDeps: {
      include: ['@temelj/result', '@temelj/async']
    }
  }
});

Performance benchmarks

Typical bundle sizes for common Temelj usage:

Bundle sizes (minified + gzipped)

@temelj/result alone:     ~1.2 KB
@temelj/async alone:      ~3.5 KB
@temelj/value alone:      ~2.1 KB
@temelj/string alone:     ~1.8 KB

All core packages:        ~7.5 KB
Complete library:        ~15 KB

These sizes include all exports. With tree shaking, your actual bundle will typically be 40-60% smaller depending on what you import.

Getting Started

Core Packages

Data & Utilities

Web & Templating

Guides

Bundling with build tools

Package structure

Vite

Basic configuration

Library mode

Webpack

TypeScript with Webpack

esbuild

Rollup

Turborepo (monorepo builds)

Bundle size optimization

Tree shaking

Code splitting

Dependency analysis

Production optimization

Environment-specific builds

Compression

Testing bundled output

Common bundling issues

Module resolution errors

Dual package hazard

Framework-specific guides

Performance benchmarks

Build docs developers (and LLMs) love

Getting Started

Core Packages

Data & Utilities

Web & Templating

Guides

​Package structure

​Vite

​Basic configuration

​Library mode

​Webpack

​TypeScript with Webpack

​esbuild

​Rollup

​Turborepo (monorepo builds)

​Bundle size optimization

​Tree shaking

​Code splitting

​Dependency analysis

​Production optimization

​Environment-specific builds

​Compression

​Testing bundled output

​Common bundling issues

​Module resolution errors

​Dual package hazard

​Framework-specific guides

​Performance benchmarks

Build docs developers (and LLMs) love

Package structure

Vite

Basic configuration

Library mode

Webpack

TypeScript with Webpack

esbuild

Rollup

Turborepo (monorepo builds)

Bundle size optimization

Tree shaking

Code splitting

Dependency analysis

Production optimization

Environment-specific builds

Compression

Testing bundled output

Common bundling issues

Module resolution errors

Dual package hazard

Framework-specific guides

Performance benchmarks