main.js

/* globals require, __dirname, process */
const {app, BrowserWindow} = require('electron');
const path = require('path');
const url = require('url');

let win;
function createWindow(){
  win = new BrowserWindow({
    'icon': __dirname + '/icon/png/16.png',
    'minHeight': 256 + 39,
    'height': 256 + 39,
    // potential electron bug, minWidth doesn't match DOM's width (8px of extra window space on all sides?)
    'minWidth': 400 + 16,
    'width': 400 + 16,
  });
  win.setMenu(null);

  win.loadURL(url.format({
    'pathname': path.join(__dirname, 'index.html'),
    'protocol': 'file:',
    'slashes': true
  }));

  //win.webContents.openDevTools();

  win.on('closed', () => {
    win = null;
  });
}

const shouldQuit = app.makeSingleInstance((commandLine, workingDirectory) => {
  if( win ){
    if( win.isMinimized() ){
      win.restore();
    }
    win.focus();
  }
});

if( shouldQuit ){
  app.quit();
}

app.on('ready', createWindow);

app.on('window-all-closed', () => {
  if( process.platform !== 'darwin' ){
    app.quit();
  }
});

app.on('active', () => {
  if( win === null ){
    createWindow();
  }
});