Reads UTM parameters from the current URL, preferring query-string values on
window.location.search over values found in hash-fragment query strings,
and caches fresh values in sessionStorage for the rest of the tab session.
If no UTM values are present in the current URL, previously cached values
are returned (if available).
Reads UTM parameters from the current URL, preferring query-string values on
window.location.searchover values found in hash-fragment query strings, and caches fresh values insessionStoragefor the rest of the tab session.If no UTM values are present in the current URL, previously cached values are returned (if available).