Retrieve the value associated with 'key' from window.location.hash

getHashValueForKey.js

// https://developer.mozilla.org/en-US/docs/Web/API/URLSearchParams
function getHashValueForKey(key) {
  var hash = window.location.hash.substr(1);
  var searchParams = new URLSearchParams(hash);
  return searchParams.get(key);
}

Example:

https://example.com#key1=value1&key2=value2

getHashValueForKey("key1"); // returns "value1"