@jsy-lang/jsy (formerly jsy-transpile)

0.10.9 verified Fri May 01 auth: no javascript

JSY is an offside-rule (indentation-based) syntax dialect for ECMAScript that transpiles to standard JavaScript via a scanner-pass transformation, without Babel, Acorn, or any runtime dependencies. Current stable version 0.10.9. It supports modern JavaScript up to ES2025, has zero dependencies, 6300+ unit tests, and works with Rollup, ESBuild, Parcel, Vite, and Node.js --loader. Unlike CoffeeScript or Python-inspired alternatives, JSY automatically keeps pace with new ECMAScript features because its transformation only handles indentation and comments, leaving the underlying JavaScript syntax untouched. The package was renamed from jsy-transpile to @jsy-lang/jsy.

Common errors

error Error: Cannot find module 'jsy-transpile' ↓

cause Package renamed from jsy-transpile to @jsy-lang/jsy.

fix

Install @jsy-lang/jsy and update imports: 'npm install @jsy-lang/jsy' then 'import jsy from "@jsy-lang/jsy"'.

error TypeError: jsy(...) is not a function ↓

cause Attempting to use a named import { transpile } instead of default import.

fix

Use default import: 'import jsy from "@jsy-lang/jsy"'.

error Parsing error: Unexpected token (1:1) after transpiling ↓

cause Incorrectly structured JSY code, e.g., missing indentation or wrong syntax.

fix

Verify that all blocks are properly indented. JSY uses indentation to denote blocks. Use spaces consistently.

error ReferenceError: module is not defined ↓

cause Using CommonJS require in an ES module context.

fix

Use ES imports instead: 'import jsy from "@jsy-lang/jsy"'.

Warnings

breaking Package renamed from jsy-transpile to @jsy-lang/jsy. All imports using the old package name will break. ↓

fix Replace 'jsy-transpile' with '@jsy-lang/jsy' in package.json and all imports.

deprecated The old package 'jsy-transpile' on npm is no longer maintained. Use '@jsy-lang/jsy' instead. ↓

fix Run 'npm install @jsy-lang/jsy' and update imports.

gotcha The default export is the transpile function, not an object. Do not destructure { transpile }. ↓

fix Use 'import jsy from "@jsy-lang/jsy"' and call jsy(source, options).

gotcha JSY transformation is syntactical only; it does not transform JavaScript semantics. Some constructs (e.g., async/await inside indented blocks) require correct indentation to work. ↓

fix Ensure indentation is consistent (tabs or spaces, not mixed). Use 2 or 4 spaces per level.

breaking Options for transpile function have changed between pre-0.10 and 0.10+. The 'module' option now defaults to false. ↓

fix Explicitly set 'module: true' if you want ES module output.

Install

npm install jsy-transpile

yarn add jsy-transpile

pnpm add jsy-transpile

Imports

default (transpile)
wrong
```
import { transpile } from '@jsy-lang/jsy'
```
correct
```
import jsy from '@jsy-lang/jsy'
```
Default export is the transpile function. Named export 'transpile' does not exist.
transpile
wrong
```
const jsy = require('jsy-transpile');
```
correct
```
import jsy from '@jsy-lang/jsy'; const result = jsy(code, options);
```
Package renamed from jsy-transpile to @jsy-lang/jsy starting from v0.10.0. Use the scoped package.
transpile (CommonJS)
wrong
```
const jsy = require('jsy-transpile');
```
correct
```
const jsy = require('@jsy-lang/jsy');
```
If using CommonJS, require the new scoped package. The old package jsy-transpile is deprecated.

Quickstart

Transpiles a simple JSY function with indentation-based syntax into standard JavaScript.

import jsy from '@jsy-lang/jsy';

const jsyCode = `
  add = (a, b) ->
    a + b

  console.log add(1, 2)
`;

const jsCode = jsy(jsyCode, {
  module: true,
  sourceType: 'module',
});

console.log(jsCode);
// Output:
// const add = (a, b) => {
//   return a + b
// }
// console.log(add(1, 2))