tish-browser-server

In-browser shims for http, fs, and process — same API surface as the host modules, implemented over Service Worker / BroadcastChannel / IndexedDB. Pure Tish, zero JS deps.

Lets capstone-style lessons in tish-learn build "server-shaped" projects (REST APIs, real-time chat, blog generators) without anyone having to deploy a backend or open a terminal. Everything runs in the learner's tab.

What you get

API surface	Real 'http' / 'fs' / 'process'	This package
serve(port, handler)	binds a TCP port, dispatches HTTP requests	registers a Service Worker that intercepts in-page fetch() and routes through your handler
new WebSocket(url) (bc://...)	opens a real socket to a remote host	a BroadcastChannel-backed shim that delivers messages between same-origin tabs
readFile/writeFile/fileExists/readDir/mkdir	reads/writes files on the host filesystem	reads/writes a virtual disk in IndexedDB; survives reload
process.env, process.argv, process.cwd, process.exit	host process info	mocked from the page's query-string + localStorage
fetch(url, opts)	network HTTP client	passthrough to native window.fetch

"Take-it-real" pattern

Every capstone in tish-learn closes with a one-line diff: change the import path and the same code runs on a real Tish server, deployable as a single binary.

- import { serve, readFile, writeFile } from "tish-browser-server"
+ import { serve } from "http"
+ import { readFile, writeFile } from "fs"

Quick example

import { serve, readFile, writeFile } from "tish-browser-server"

let notes = []
async fn loadNotes() {
  try {
    let raw = await readFile("/notes.json")
    if (typeof raw === "string") { notes = JSON.parse(raw) }
  } catch (e) { }
}
async fn saveNotes() {
  await writeFile("/notes.json", JSON.stringify(notes))
}

await loadNotes()

await serve(8080, async (req) => {
  if (req.method === "GET" && req.path === "/api/notes") {
    return { status: 200, body: notes }
  }
  if (req.method === "POST" && req.path === "/api/notes") {
    let n = JSON.parse(req.body)
    notes.push(n)
    await saveNotes()
    return { status: 201, body: n }
  }
  return { status: 404, body: "Not Found" }
})

// Now anywhere in the same tab:
//   let res = await fetch("/api/notes")
//   let list = await res.json()

Real-time chat with two tabs

import { createBcWebSocket } from "tish-browser-server"

let ws = createBcWebSocket("bc://chat/general")
ws.onopen = () => console.log("connected")
ws.onmessage = (ev) => console.log("got:", ev.data)
ws.send("hi from tab 1")

Open the same page in another tab, run the same code, and they'll see each other's messages instantly.

Service Worker setup

The host page must serve the worker script at /dist/tish-sw.js. In tish-learn we generate it via tish build --target js on node_modules/tish-browser-server/src/sw_worker.tish as part of the build. See tish-learn/justfile for the recipe.

Why "no backend" matters

tish-playground runs the entire Tish compiler + VM in the browser. We extend that promise to the curriculum: open a tab, learn, ship something — no Docker, no Heroku, no SSH. If you outgrow the browser sandbox, the take-it-real diff is one line away.

License

PIF