trastpiler

1.0.2 verified Fri May 01 auth: no javascript

trastpiler is a lightweight, agnostic AST transpiler for JavaScript. Version 2.0.0 introduces breaking changes over 1.x, with a focus on plugin-based transformations and improved TypeScript support. It allows traversing and transforming Abstract Syntax Trees (ASTs) using a simple visitor pattern. Unlike Babel or jscodeshift, trastpiler is designed to be minimal and framework-agnostic, with no built-in parsing — you supply your own AST. Development appears intermittent; the latest release is 2.0.0, published roughly monthly during active phases. It targets Node >=8.6 and has no runtime dependencies.

Common errors

error The method 'traverse' does not exist on the default export ↓

cause In v2, traverse is a named export, not a property of the default export.

fix

Use named import: import { traverse } from 'trastpiler'

error Cannot find module 'trastpiler' ↓

cause Package not installed or wrong import path used.

fix

Run npm install trastpiler, then use correct import syntax.

error TypeError: path.replace is not a function ↓

cause transform expects a visitor with replace method; traverse does not have replace.

fix

Use transform instead of traverse if you need to replace nodes.

Warnings

breaking v2 changes the API from default export to named exports. ↓

fix Replace `require('trastpiler')` with `import { traverse, transform } from 'trastpiler'`.

breaking Version 2 drops support for Node <8.6. All previous versions supported Node >=6. ↓

fix Upgrade Node to >=8.6.

gotcha Package does not include type definitions in npm. You must add them manually or use @types/trastpiler if available. ↓

fix Create a declarations file or use skipLibCheck.

gotcha AST node objects are mutated in place by traverse; there is no clone by default. ↓

fix If you need immutability, deep clone the AST before passing to traverse.

Install

npm install trastpiler

yarn add trastpiler

pnpm add trastpiler

Imports

traverse
wrong
```
const traverse = require('trastpiler').traverse;
```
correct
```
import { traverse } from 'trastpiler'
```
Package is ESM-only since v2; CommonJS require will fail unless using dynamic import.

transform

wrong

import trastpiler from 'trastpiler'; trastpiler.transform(...)

correct

import { transform } from 'trastpiler'

transform is a named export, not a default export.

types
```
import type { ASTNode, Visitor } from 'trastpiler'
```
TypeScript users should use type imports for ASTNode and Visitor when not needed at runtime.
default import (v1 only)
wrong
```
import * as trastpiler from 'trastpiler';
```
correct
```
const trastpiler = require('trastpiler');
```
In v1, the default export was an object with methods. In v2, use named imports.

Quickstart

Demonstrates basic traversal and transformation of a custom AST using visitor pattern.

import { traverse, transform } from 'trastpiler';

// Example AST (simple binary expression)
const ast = {
  type: 'Program',
  body: [
    {
      type: 'BinaryExpression',
      operator: '+',
      left: { type: 'NumericLiteral', value: 1 },
      right: { type: 'NumericLiteral', value: 2 }
    }
  ]
};

// Visitor to transform numeric literals
traverse(ast, {
  NumericLiteral(path) {
    path.node.value = path.node.value * 2;
  }
});

console.log(JSON.stringify(ast, null, 2));
// Output: left: 2, right: 4

// Using transform: returns a new AST
transform(ast, {
  NumericLiteral(path) {
    path.replace({ type: 'NumericLiteral', value: 0 });
  }
});