starting to clean up url hash handling code

covid.js

@@ -995,6 +995,22 @@ let calculateAverageRate = (data) => {
   return a / (data.length - 1)
 }
 
+
+/*
+ * assemble and set the url hash
+ * without firing a hashchange event
+ */
+let setUrlHash = () => {
+    var selected_sites = []
+    for (let sselect of sitesSelects) {
+        selected_sites.push(sselect.value.toLowerCase().replace(/[^a-z0-9]/g, '-'))
+    }
+    // using History.pushState() because we don't want the onhashchange event to fire
+    history.pushState({}, '', '#' + selected_sites.join(','))
+}
+
+
+
 /*
  * handling a .sites-select change
  */
@@ -1015,12 +1031,8 @@ let selectSite = (e) => {
     // need to handle the corner cases, eh
     var site = theSelect.value
 
-    var selected_sites = []
-    for (let sselect of sitesSelects) {
-        selected_sites.push(sselect.value.toLowerCase().replace(/[^a-z0-9]/g, '-'))
-    }
-    // using History.pushState() because we don't want the onhashchange event to fire
-    history.pushState({}, '', '#' + selected_sites.join(','))
+    // set the URL hash without firing the hashchange event
+    setUrlHash()
 
     // using a timeout to give the user a chance to change their mind
     theSelect.selectTimeout = setTimeout(function(){
@@ -2006,7 +2018,9 @@ document.addEventListener('DOMContentLoaded', (e)=>{
             sitesSelects[0].value = "select one"
         }
         // using History.pushState() because we don't want the onhashchange event to fire
-        history.pushState({}, '', window.location.hash.replace(/,[^,]+$/, ''))
+        setUrlHash()
+        
+        // update the chart
         updateChartSettings()
     })