Handles Electron app.asar updates.

Usage no npm install needed!

<script type="module">
  import electronAsarHotUpdater from 'https://cdn.skypack.dev/electron-asar-hot-updater';



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Update demo

What it is

A NodeJs module for Electron, that handles app.asar updates. Reconstruction of electron-asar-updater

How it works (Read this first)

  • EAU (Electron Asar Updater) was built upon Electron Application Updater to handle the process of updating the app.asar file inside an Electron app ; it simply replaces the app.asar file (at /resources/) with the new one called "update.asar"!
  • The check for "updates" must by triggered by the application. EAU doesn't make any kind of periodic checks on its own.
  • EAU talks to an API (let's call it so) to tell it if there is a new update.
    • The API receives a request from EAU with the client's current version of the application (must be specified inside the application package.json file).
    • The API then responds with the new update, ... or simply false to abort.
    • If there's an update available the API should respond with the source for this update update.asar file.
    • EAU then downloads the .asar file, deletes the old app.asar and renames the update.asar to app.asar.

But why ? (use cases)


$ npm install --save electron-asar-hot-updater

Now, inside the main.js file, call it like this:

const { app, dialog } = require('electron');
const EAU = require('electron-asar-hot-updater');

app.on('ready', function () {
  // Initiate the module
    'api': 'http://...', // The API EAU will talk to
    'server': false, // Where to check. true: server side, false: client side, default: true.
    'debug': false, // Default: false.
    'headers': { Authorization: 'token' }, // Default: {}
    'body': {
      name: packageInfo.name,
      current: packageInfo.version
    }, // Default: name and the current version
    'formatRes': function(res) { return res } // Optional,Format the EAU.check response body, exemple => {version: xx, asar: xx}

  EAU.check(function (error, last, body) {
    if (error) {
      if (error === 'no_update_available') { return false; }
      if (error === 'version_not_specified' && process.env.NODE_ENV === 'development') { return false } // Don't worry about this error when developing
      dialog.showErrorBox('info', error)
      return false

    EAU.progress(function (state) {
      // The state is an object that looks like this:
      // {
      //     percent: 0.5,               
      //     speed: 554732,              
      //     size: {
      //         total: 90044871,        
      //         transferred: 27610959   
      //     },
      //     time: {
      //         elapsed: 36.235,        
      //         remaining: 81.403       
      //     }
      // }

    EAU.download(function (error) {
      if (error) {
        dialog.showErrorBox('info', error)
        return false
      // dialog.showErrorBox('info', 'App updated successfully! Restart it please.')
      if (process.platform === 'darwin') {
      } else {


The update server

The server can return the version details, for example

const express = require('express')
var bodyParser = require('body-parser');
const app = express()

app.use(bodyParser.urlencoded({ extended: false }));

var desktop_app_version = '1.0.0';
var desktop_app_URL = '' // or ../update.zip

app.post('/update', function (req, res) {
  if(req.body && req.body.current != desktop_app_version){ // check for server side
    res.write(JSON.stringify( {"last": desktop_app_version, "source": desktop_app_URL} ).replace(/[\/]/g, '\\/') );
    res.write(JSON.stringify( {"last": desktop_app_version} ).replace(/[\/]/g, '\\/') );

console.log('run port: 3000')

Or you can return version information for client to check

app.post('/update', function (req, res) {
  res.write(JSON.stringify( {
    "name": "app",
    "version": "0.0.1",
    "asar": "",
    "sha1": "203448645d8a32b9a08ca9a0eb88006f874d0c78", // Optional, If set, verify `asar` file legitimacy
    "info": "1.fix bug\n2.feat..."
  } ).replace(/[\/]/g, '\\/') );

If you use a zip file, the plug-in will unzip the file after downloading it, which will make your update file smaller, but you must make sure that update.asar is at the root of the zip package:

── update.zip
   └── update.asar

Now uses a really dumb-but-simple .exe to update

This is to get around the fact that the prompt text from the timeout command was always being shown, even when redirecting to NUL

The updater.exe is a really simple C# console app, compiled with Mono. Source code. from electron-asar-updater pull #2. If the user system version is win7, you may need to manually install .Net framework first.


:smiley: if you have any comments or wish to contribute to this project, you are welcome to submit Issues or PR.

MIT - yansenlei