Prevent Electron from closing the main window if there are unsaved changes

prevent-window-close-in-electron.coffee

# In main.coffee

closeAfterSave = false

mainWindow.on 'close', (event) ->
    if !closeAfterSave
      event.preventDefault()
      mainWindow.webContents.send 'closingWindow'
    return
	
ipc.on 'doClose', ->
    closeAfterSave = true
    mainWindow.close()
    return
	
	
# In app.coffee

ipc.on 'closingWindow', (event) ->
  if !file.saved
    result = dialog.showMessageBox(remote.getCurrentWindow(),
      type: 'warning'
      buttons: [
        'Save'
        'Cancel'
        'Don\'t Save'
      ]
      title: 'Save changes?'
      message: 'You have unsaved changes. Would you like to save them first?'
      detail: 'Your changes will be lost if you don\'t save them.')
    if result == 0
      handleSaveRequest()
    else if result == 1
      return false
  ipc.send 'doClose'
  return