Small function to check if any GA4 Container has been currently been loaded.

getLoadedGA4Containers.js

// DV - 2022 - ES5
// Check if GA4 has been loaded

var getLoadedGA4Containers = function() {  
  return Object.keys(
    window.google_tag_data && 
    window.google_tag_data.tidr && 
    window.google_tag_data.tidr.container || {}
  ).filter(function(e){ return e.startsWith('G-') })
}

//ES6 Version
const getLoadedGA4Containers = () => {
  return Object.keys(
    window.google_tag_data?.tidr?.container || {}).filter(e => e.startsWith('G-')
  )
}