Get the data layer as an object from Google Tag Manager

getDataLayerObject.js

var getDataLayerObject = function getDataLayerObject (gtmid) {
  var keys = Object.keys(Object.assign(...dataLayer)) || []
  var data = {}

  keys.forEach(function (key) {
    key = key.split(/\./gu)[0]

    if (data[key] === undefined) data[key] = google_tag_manager[gtmid].dataLayer.get(key)
  })

  return data
}