Traceur Compiler

0.0.111 verified Fri May 01 auth: no javascript maintenance

Traceur is a JavaScript.next-to-JavaScript-of-today compiler that allows you to use ES6 and experimental ES.next features by transpiling them to ES5. Version 0.0.111 is the latest stable release. It was developed by Google to inform the design of new JavaScript features and supports a wide range of proposals including async functions, generators, spread properties, and JSX. It provides both CommonJS and browser builds. Traceur is now largely superseded by Babel, but remains useful for legacy projects or understanding early transpiler design.

Common errors

error Cannot find module 'traceur/dist/commonjs/Compiler' ↓

cause The Compiler module was restructured in 0.0.108 and is no longer at the old path.

fix

Use: const { Compiler } = require('traceur/dist/commonjs/Compiler');

error TypeError: traceur.compile is not a function ↓

cause The compile function is deprecated and not exported as a standalone function in some versions.

fix

Use the Compiler class or ensure you are using a version that exports compile (e.g., <0.0.108).

error ReferenceError: require is not defined ↓

cause Trying to use Traceur in a browser environment without a bundler.

fix

Use the browser build: <script src='node_modules/traceur/bin/traceur.js'></script>

error Error: Cannot find module 'glob' ↓

cause Missing optional dependency 'glob' which is required for some internal operations.

fix

Install 'glob' as a dependency: npm install glob

Warnings

breaking The Compiler class is no longer exported from the main 'traceur' module. Import it from 'traceur/dist/commonjs/Compiler' instead. ↓

fix Change import from require('traceur').Compiler to require('traceur/dist/commonjs/Compiler').Compiler

deprecated The `compile` function exported from the main module is deprecated in favor of using the Compiler class. ↓

fix Use Compiler instance: new Compiler().compile()

gotcha When using the command-line tool, you must install Traceur globally or use npx. The bin/traceur file may have a shebang issue on Windows. ↓

fix Use `npx traceur` or install globally: `npm install -g traceur`

breaking In version 0.0.108, runtime modules were moved into individual modules under 'traceur/dist/commonjs/runtime/modules/'. Requiring the full runtime is no longer sufficient. ↓

fix Import specific runtime modules as needed, e.g., require('traceur/dist/commonjs/runtime/modules/call.js')

deprecated The `--experimental` flag has been deprecated and may not work as expected in recent versions. ↓

fix Use specific feature flags like `--async-functions` instead.

gotcha Node.js must be >=0.10 (engines field). Using Traceur with very old Node <0.10 will fail. ↓

fix Update Node.js to >=0.10 or use an older version of Traceur.

Install

npm install traceur

yarn add traceur

pnpm add traceur

Imports

traceur
wrong
```
import traceur from 'traceur';
```
correct
```
const traceur = require('traceur');
```
Traceur uses CommonJS. ESM import may fail in Node < 13 or without proper configuration.

compile

wrong

const compile = require('traceur').compile;

correct

const { compile } = require('traceur');

Deprecated: access via destructuring is preferred since 0.0.108.

TraceurCompiler
wrong
```
const Compiler = require('traceur').Compiler;
```
correct
```
const { Compiler } = require('traceur/dist/commonjs/Compiler');
```
The Compiler class is not exported from the main entry point; it must be imported from the specific module path.

Quickstart

Compiles an ES6 file to CommonJS with error handling and optional source maps.

const traceur = require('traceur');
const fs = require('fs');

const code = fs.readFileSync('example.es6', 'utf8');
try {
  const result = traceur.compile(code, {
    sourceMaps: false,
    modules: 'commonjs'
  });
  if (result.errors && result.errors.length) {
    console.error('Errors:', result.errors);
  } else {
    console.log(result.js);
    if (result.sourceMap) {
      console.log('Source map generated');
    }
  }
} catch (e) {
  console.error('Compilation failed:', e);
}