# Esupgrade

> Auto-update JavaScript and TypeScript syntax to new ECMAScript features based on browser support. Use when the user asks to modernize, upgrade, or clean up JavaScript or TypeScript syntax.

- Skill: `codingjoe/esupgrade` (Agent Skill)
- Install (CLI): `npx skillmds@latest add codingjoe/esupgrade`
- Raw SKILL.md: https://api.skillmd.com/api/skills/codingjoe/esupgrade/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: codingjoe (https://skillmd.com/u/codingjoe)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/codingjoe/esupgrade

---


Use the CLI with `npx` on files, directories, or standard input:

```console
npx -y esupgrade [--baseline <newly-available|widely-available>] [--check] [--write] <files-or-directories|->
```

- Use `--check` to preview changes and fail when updates are needed.
- Use `-` to read from standard input and write the transformed code to standard output.
- Use `--write` to apply updates in place for file inputs.
- Use `--baseline` to choose `newly-available` or `widely-available` (default).