Publishing OCaml to npm via js_of_ocaml and wasm_of_ocaml. Use when discussing browser targets, JavaScript compilation, WASM output, npm packages, or the two-branch workflow.
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ocaml-dev
January 20, 2026
Select agents to install to:
npx add-skill https://github.com/avsm/ocaml-claude-marketplace/blob/main/plugins/ocaml-dev/skills/ocaml-npm-publishing/SKILL.md -a claude-code --skill ocaml-npm-publishingInstallation paths:
.claude/skills/ocaml-npm-publishing/# OCaml to NPM Publishing
## When to Use This Skill
Invoke this skill when:
- Setting up npm publishing for OCaml projects
- Configuring js_of_ocaml or wasm_of_ocaml
- Discussing browser targets for OCaml
- Creating the npm branch workflow
## Branch Structure
```
main branch - OCaml source code, dune build files, opam packages
npm branch - Built JavaScript/WASM assets, package.json, README for npm
```
The `npm` branch is an orphan branch with no shared history.
## Dune Build Rules
### Library with Browser Bindings
In `lib/js/dune`:
```dune
; Library compiled to bytecode (required for js_of_ocaml)
(library
(name mylib_js)
(public_name mylib-js)
(libraries mylib brr)
(modes byte)
(modules mylib_js))
; Executable compiled to both JS and WASM
(executable
(name mylib_js_main)
(libraries mylib_js)
(js_of_ocaml)
(modes js wasm)
(modules mylib_js_main))
; Friendly filename for JS
(rule
(targets mylib.js)
(deps mylib_js_main.bc.js)
(action (copy %{deps} %{targets})))
; Friendly filename for WASM
(rule
(targets mylib.wasm.js)
(deps mylib_js_main.bc.wasm.js)
(action (copy %{deps} %{targets})))
; Install web assets
(install
(package mylib-js)
(section share)
(files
mylib.js
mylib.wasm.js
(glob_files_rec (mylib_js_main.bc.wasm.assets/* with_prefix mylib_js_main.bc.wasm.assets))))
```
### dune-project Package
```dune
(package
(name mylib-js)
(synopsis "Browser library via js_of_ocaml/wasm_of_ocaml")
(depends
(ocaml (>= 5.1.0))
(mylib (= :version))
(js_of_ocaml (>= 5.0))
(js_of_ocaml-ppx (>= 5.0))
(wasm_of_ocaml-compiler (>= 5.0))
(brr (>= 0.0.6))))
```
## Creating the NPM Branch
```bash
# Create orphan branch
git switch --orphan npm
# Add npm-specific files
git add package.json README.md LICENSE release.sh .gitignore
git commit -m "Initial npm package setup"
# Switch back
git checkout main
```
## NPM Branch Files
See `templates/` for:
- `package.json.template`
- `release.sh.template`
### package.json
```json