QuickJS

QuickJS runs node and js: a bare ES2023 engine in WebAssembly, inside the Mirage process, for small scripts and pipe transforms. It is not Node: there is no require, npm, fs or fetch. The files it opens are the workspace’s, under the same mount modes and permissions as shell commands. It is in the default runtimes of both SDKs.

Installation

Python
TypeScript

pip install 'mirage-ai[quickjs]'

Download qjs-wasi.wasm from a quickjs-ng release. Point home, or MIRAGE_QUICKJS_HOME, at its directory.

pnpm add quickjs-emscripten

The package bundles its WebAssembly.

Usage

QuickJS is in the default runtimes, so node works once it is installed. To list it yourself:

Python
TypeScript
YAML

from mirage import RAMVFS, MountMode, Workspace
from mirage.runtime.js import QuickJsRuntime

ws = Workspace(
    {"/data": RAMVFS()},
    mode=MountMode.EXEC,
    runtimes=[QuickJsRuntime(config={"home": "/path/to/quickjs"})],
)
await ws.shell("node -e 'console.log(1 + 1)'")

import { MountMode, RAMVFS, Workspace } from '@struktoai/mirage-node'

const ws = new Workspace({ '/data': new RAMVFS() }, { mode: MountMode.EXEC, runtimes: ['quickjs'] })
await ws.shell("node -e 'console.log(1 + 1)'")

mode: exec
runtimes:
  - name: quickjs
    config:
      home: /path/to/quickjs
mounts:
  /data:
    vfs: ram

home is for the Python SDK; TypeScript ignores it.

What is wired

std and os are globals, as in qjs --std.

JavaScript	Python SDK	TypeScript SDK	Notes
`std.open(path, mode, errorObj)`, modes `r`, `w`, `a`, `+`, `x`, `b`	Yes	Yes	`null` on failure, with `errorObj.errno`. A read-only mount refuses only the modes that write.
FILE `readAsString`, `read`, `getline`, `seek`, `tell`, `eof`	Yes	Yes
FILE `puts`, `write`	Yes	Yes	Written at `close`, or when the run ends.
FILE `flush`	Yes	Does nothing
FILE `printf`, `tello`	Yes	No
`os.readdir`, `os.stat`	Yes	Yes	Return `[value, errno]`. In Python, `mode` has only the file type bits.
`os.mkdir`, `os.remove`, `os.utimes`	Yes	Yes	`os.remove` also removes an empty directory.
`os.rename`	Yes	Yes	`-75` (`EXDEV`) across mounts.
`os.getcwd`, `os.chdir`	Yes	Yes	The shell’s working directory; a change lasts for the run.
`std.getenv`	Yes	Yes	The session’s environment.
`scriptArgs`, `std.in.readAsString()`	Yes	Yes	The words after the script, and the piped input.
`std.out.puts`, `std.err.puts`, `console.log`, `print`, `std.exit`	Yes	Yes
`std.out.printf`, `std.err.printf`	Yes	Yes	C format; return the characters written. Unlike `printf` on an opened FILE.
`std.loadFile`, `std.writeFile`, `std.fdopen`, `std.printf`	Yes	No
`std.strerror`, `std.setenv`, `std.getenviron`, `std.out.flush`	Yes	No
`os.open`, `os.read`, `os.write`, `os.seek`, `os.close`	Yes	No
`os.sleep`, `os.setTimeout`	Yes	No
`os.lstat`, `os.symlink`, `os.readlink`, `os.realpath`	No	No
`os.exec`, `std.popen`, `std.tmpfile`	No	No
`console.error`, `setTimeout`, `fetch`, `require`, `process`	No	No

In TypeScript, any std or os function not listed as supported throws TypeError.

Notes

-e <code> runs the argument, a file runs a mounted script, and with neither, piped input is the program. A .mjs file runs as an ES module; .js and -e run as classic scripts, and -m forces module mode.
console.log and print add a newline; std.out.puts and std.err.puts write raw.
QuickJS cannot reach host files or the network, but only command_limits bound its CPU and memory. Run untrusted or heavy code in a sandbox.
QuickJS can evaluate expressions, so it can run a route policy: route_policy: ./policy.js runs per line with ctx as a global, and the last expression names the runtime.

Getting Started

Access

Policy

Learn

Integration

Help

VFS

CLIs

Runtimes

Installation

Usage

What is wired

Notes

​Installation

​Usage

​What is wired

​Notes

Installation

Usage

What is wired

Notes