# arepl-backend > JS interface to python evaluator for AREPL Latest version **4.0.0** (published 2025-08-17) · MIT license · 0 weekly downloads ## Install ```sh npm install arepl-backend pnpm add arepl-backend yarn add arepl-backend bun add arepl-backend ``` ## Health **Score 40/100 (D)** — status: stable. Positive: no vulnerabilities; high maintenance score. Warnings: low downloads; no types; no esm support. Negative: stale. ## Facts | | | |---|---| | Version | 4.0.0 | | Published | 2025-08-17 | | First published | 2017-12-24 | | Weekly downloads | 0 | | License | MIT | | TypeScript types | none | | Module format | CommonJS | | Dependencies | 1 | | Unpacked size | 272.5 KB | | Known vulnerabilities | 0 | | Install scripts | no | | GitHub stars | 14 | | Author | Almenon | | Maintainers | almenon | | Keywords | IDE, python, real-time, AREPL | ## Links - npm: https://www.npmjs.com/package/arepl-backend - Repository: https://github.com/Almenon/arepl-backend - Homepage: https://github.com/Almenon/arepl-backend#readme - Issues: https://github.com/Almenon/arepl-backend - npm.io page: https://npm.io/package/arepl-backend ## Dependencies (1) - [python-shell](https://npm.io/package/python-shell.md) ^5.0.0 ## Alternatives - [adhdev](https://npm.io/package/adhdev.md) — 11.1K weekly downloads - [react-slide-button](https://npm.io/package/react-slide-button.md) — 310 weekly downloads - [better](https://npm.io/package/better.md) — 42 weekly downloads - [react-native-swipe-image](https://npm.io/package/react-native-swipe-image.md) — 22 weekly downloads - [nl.fokkezb.pulltorefresh](https://npm.io/package/nl.fokkezb.pulltorefresh.md) — 11 weekly downloads ## Recent versions - 4.0.0 (latest) — 2025-08-17 - 3.0.5 — 2024-11-18 - 3.0.4 — 2024-11-17 - 3.0.3 — 2024-11-15 - 3.0.2 — 2024-11-15 - 3.0.1 — 2024-11-15 - 3.0.0 — 2024-11-14 - 2.1.0 — 2023-03-06 - 2.0.2 — 2022-10-23 - 2.0.1 — 2021-05-11 - 1.3.15 — 2021-03-27 - 1.3.14 — 2020-11-21 - 1.3.13 — 2020-11-21 - 2.0.3 — 2020-11-20 - 1.3.12 — 2020-11-01 - … 56 more at https://npm.io/package/arepl-backend/versions ## README # AREPL-backend [![npm version](https://badge.fury.io/js/arepl-backend.svg)](https://badge.fury.io/js/arepl-backend) ![example workflow](https://github.com/almenon/AREPL-backend/actions/workflows/tests.yml/badge.svg) JS interface to python evaluator for AREPL. Evaluates python code and sends back the user variables and/or any errors. Although it is meant for AREPL, it is not dependent upon AREPL and can be used by any project. **Important Note**: this should ONLY be used to execute trusted code. It does not have any security features whatsoever. ## Installation > npm install [arepl-backend](https://www.npmjs.com/package/arepl-backend) Must have python 3.8 or greater ## Usage see for example useage. ## For developers: Semantic release cheatsheet: | Commit message | Release type | |----------------------|--------------| | fix: msg | patch | | feat: msg | feature | | perf: msg | | | BREAKING CHANGE: msg | breaking | ## API #### Table of Contents * [PythonState](#pythonstate) * [constructor](#constructor) * [Parameters](#parameters) * [execCode](#execcode) * [Parameters](#parameters-1) * [sendStdin](#sendstdin) * [Parameters](#parameters-2) * [restart](#restart) * [Parameters](#parameters-3) * [stop](#stop) * [Parameters](#parameters-4) * [start](#start) * [Parameters](#parameters-5) * [onResult](#onresult) * [Parameters](#parameters-6) * [onPrint](#onprint) * [Parameters](#parameters-7) * [onStderr](#onstderr) * [Parameters](#parameters-8) * [handleResult](#handleresult) * [Parameters](#parameters-9) * [checkSyntax](#checksyntax) * [Parameters](#parameters-10) * [formatPythonException](#formatpythonexception) * [Parameters](#parameters-11) * [Examples](#examples) ### PythonState Starting = Starting or restarting. Ending = Process is exiting. Executing = Executing inputted code. DirtyFree = evaluator may have been polluted by side-effects from previous code, but is free for more code. FreshFree = evaluator is ready for the first run of code ### constructor starts python\_evaluator.py #### Parameters * `options` Process / Python options. If not specified sensible defaults are inferred. (optional, default `{}`) ### execCode does not do anything if program is currently executing code #### Parameters * `code` ### sendStdin #### Parameters * `message` **[string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** ### restart kills python process and restarts. Force-kills if necessary after 50ms. After process restarts the callback passed in is invoked #### Parameters * `callback` (optional, default `()=>{}`) ### stop Kills python process. Force-kills if necessary after 50ms. You can check python\_evaluator.running to see if process is dead yet #### Parameters * `kill_immediately` (optional, default `false`) ### start starts python\_evaluator.py. Will NOT WORK with python 2 #### Parameters * `finishedStartingCallback` ### onResult Overwrite this with your own handler. is called when program fails or completes #### Parameters * `foo` ### onPrint Overwrite this with your own handler. Is called when program prints #### Parameters * `foo` **[string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** ### onStderr Overwrite this with your own handler. Is called when program logs stderr #### Parameters * `foo` **[string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** ### handleResult handles pyshell results and calls onResult / onPrint #### Parameters * `results` **[string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** ### checkSyntax checks syntax without executing code #### Parameters * `code` **[string](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** Returns **[Promise](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Promise)** rejects w/ stderr if syntax failure ### formatPythonException gets rid of unnecessary File "" message in exception #### Parameters * `err` #### Examples ```javascript err: Traceback (most recent call last):\n File "", line 1, in \nNameError: name \'x\' is not defined\n ``` --- _Source: https://npm.io/package/arepl-backend · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._