mts-migrator

library2.1.11jsnpmunverified

mts-migrator is a javascript-to-typescript migration engine that converts CommonJS modules to ESM, infers types from AST analysis, extracts JSDoc annotations, and refines types with the TypeScript compiler using ts-morph. Current stable version is 2.1.11, released under AGPL-3.0. It can be used via `pnpm dlx` or `npx` without installation. Key differentiators: it handles module system conversion (require→import, module.exports→export), deduplicates imports, strips .js/.jsx from relative imports, infers types from literals, constructors, known APIs, arrays, binary ops, and JSDoc, and optionally runs eslint --fix. It backs up original files, supports dry runs, error recovery, migration reports, and skips config files. Does not handle Flow types or fix logic bugs.

devops

npm install mts-migrator

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · MTS-MIGRATOR

mts-migrator

devopsjavascriptv2.1.11

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

migrateCode

✓ import { migrateCode } from 'mts-migrator'

✗ const migrateCode = require('mts-migrator')

Package is ESM-only. Named export, not default.

migrateCodeSimple

✓ import { migrateCode } from 'mts-migrator'

migrateCode is the main function for quick code conversion.

codeToAST

✓ import { codeToAST } from 'mts-migrator'

✗ import { codeToAst } from 'mts-migrator'

Export name is camelCase: codeToAST, not codeToAst.

convertModuleSystem

✓ import { convertModuleSystem } from 'mts-migrator'

Converts CommonJS modules to ESM in an AST.

injectTypes

✓ import { injectTypes } from 'mts-migrator'

Injects type annotations into an AST.

astToCode

✓ import { astToCode } from 'mts-migrator'

Converts an AST back to code string.

Shows basic usage of the migrateCode function to convert CommonJS to ESM with type inference.

import { migrateCode } from 'mts-migrator'; const jsCode = ` const fs = require('fs'); const { join } = require('path'); module.exports = function readConfig(filePath) { const data = fs.readFileSync(join(__dirname, filePath), 'utf8'); return JSON.parse(data); }; `; const result = migrateCode(jsCode); console.log(result.code); // Output: // import fs from 'fs'; // import { join } from 'path'; // // export function readConfig(filePath: string): any { // const data = fs.readFileSync(join(__dirname, filePath), 'utf8'); // return JSON.parse(data); // }

Debug

Known issues

gotchaThe migrateCode function returns an object with code and errors; errors are non-fatal but should be inspected.

fix

Check result.errors for migration warnings or issues.

affects: >=2.0

gotchaType refinement using ts-morph requires TypeScript to be installed; otherwise, any annotations may remain.

fix

Install typescript as a devDependency: pnpm add -D typescript

affects: >=2.0

gotchaThe CLI command is 'mts' not 'mts-migrator'; running without arguments prompts to migrate all folders in current directory.

fix

Use 'pnpm mts' or 'npx mts-migrator' but note that the binary name is 'mts'.

affects: >=2.0

gotchaOriginal files are backed up before migration; backup directory is created alongside the original files.

fix

To restore, copy files from .mts-backups or similar (check documentation for exact backup folder name).

affects: >=2.0

deprecatedNo breaking changes identified in current version; API is stable.

affects: >=2.1

Errors

Common errors & fixes

Error [ERR_REQUIRE_ESM]: require() of ES Module not supported

Using CommonJS require() to import an ESM-only package.

fix

Use import syntax or switch to ESM in your project (add 'type': 'module' to package.json).

TypeError: migrateCode is not a function

Package is ESM-only; using require() returns the module object, not the named export.

fix

Use dynamic import: const { migrateCode } = await import('mts-migrator'); or use ESM import syntax.

Cannot find module 'mts-migrator'

Package is not installed or not in node_modules.

fix

Install it: pnpm add mts-migrator or npm install mts-migrator

Type 'string' is not assignable to type 'number'

Type inference may produce incorrect types due to dynamic code; manual annotation needed.

fix

Add explicit type annotations where inference fails.

Upgrade

Version history

2.1.11latest on npm

Audit

Dependencies

typescriptoptionalts-morph uses the TypeScript compiler for type refinement; TypeScript must be installed in the project for full functionality.

@ts-morph/bootstraprequiredUsed for programmatic type refinement with the TypeScript compiler API.

@babel/parserrequiredParses JavaScript code into AST for analysis and transformation.

@babel/traverserequiredTraverses and transforms the AST during migration.

eslintoptionalRuns eslint --fix on migrated files if available in the project.

Agent activity

4 hits · last 30 days

node

Resources

githubhttps://github.com/LaxentaInc/Magikk-Typescript-Migrator ↗

packagemts-migrator ↗

homepagehttps://colorwall.xyz ↗