Make Google Apps Script Add-on available to all Google Editor Apps

Question

I have written a simple sidebar for Google Slides that makes a REST call and fetches some images. The user can then Copy-Paste some of these images to their document if they wish. However, my code doesn't depend on or use any Google Slides-specific functionality, and I want to also make it available to Google Docs and Sheets.

Is there any easy way of doing this, without creating a separate app for each Editor program?

I was looking at this Reference page hoping to find a parent class to all DocumentApp, SlidesApp and SheetsApp, but couldn't. Google does define "Utility Services" here, which are not supposed to be tied to any specific App, but I cannot use it because my code needs the "SlidesApp" object to create the Sidebar. Is there a way to decouple Sidebar creation from the specific Google Editor app?

// https://developers.google.com/apps-script/guides/dialogs#custom_sidebars
function onOpen() {
  SlidesApp.getUi() // Or DocumentApp or SlidesApp or FormApp.
      .createMenu('Image Search')
      .addItem('Show sidebar', 'showSidebar')
      .addToUi();
}

function showSidebar() {
  var html = HtmlService.createHtmlOutputFromFile('Page')
      .setTitle('Image Search');
  SlidesApp.getUi() // Or DocumentApp or SlidesApp or FormApp.
      .showSidebar(html);
}

Answer 1

In addition to the solutions provided in the related post mentioned by @TheMaster, you can also implement a simple try...catch statement:

function onOpen() {
  try{
    SlidesApp.getUi() // Or DocumentApp or SlidesApp or FormApp.
    .createMenu('Image Search')
    .addItem('Show sidebar', 'showSidebar')
    .addToUi();    
  }
  catch(e){
    try{
      DocumentApp.getUi() // Or DocumentApp or SlidesApp or FormApp.
      .createMenu('Image Search')
      .addItem('Show sidebar', 'showSidebar')
      .addToUi();   
    }
    catch(e){
      SpreadsheetApp.getUi() // Or DocumentApp or SlidesApp or FormApp.
      .createMenu('Image Search')
      .addItem('Show sidebar', 'showSidebar')
      .addToUi();
    }
  }
}