Update page URL to match molecule currently displayed

src/coffee/main.coffee

@@ -146,7 +146,21 @@ $(document).ready ->
       url = buildSmilesUrl screenWidth, screenHeight, foregroundColor, backgroundColor, currentCompoundSmiles
     downloadButton.attr 'download', if smilesMode then 'smiles_molecule' else currentCompoundName
     downloadButton.attr 'href', url
-    
+
+  # Updates the page URL (query string) according to the currently displayed molecule.
+  #
+  updateUrl = ->
+    params = {
+      'label': customLabel,
+      'background': backgroundColor,
+      'foreground': foregroundColor
+    }
+    if smilesMode
+      params['smiles'] = currentCompoundSmiles
+    else
+      params['compound'] = currentCompoundName
+    setQueryParams params
+
   # Updates the displayed preview.
   #
   # @param [object] element     the element to update
@@ -159,6 +173,7 @@ $(document).ready ->
     element.css 'background-position', '50% 50%'
     element.css 'background-repeat', 'no-repeat'
     updateDownloadLink()
+    updateUrl()
 
   # Refreshes the preview using the compound name text box.
   #

src/coffee/params.coffee

@@ -14,3 +14,24 @@ window.getParameterByName = (name, url) ->
   if !results[2]
     return ''
   decodeURIComponent results[2].replace(/\+/g, ' ')
+
+# Sets the query string on the page without reloading it.
+#
+# @param [string] str the new query string
+#
+window.setQueryString = (str) ->
+  if history.pushState
+    url = window.location.protocol + '//' + window.location.host + window.location.pathname + '?' + str
+    window.history.pushState { path: url }, '', url
+
+# Sets the query string on the page without reloading it, according to the properties of an object.
+#
+# @param [object] params  the object containing the keys and values to use
+#
+window.setQueryParams = (params) ->
+  str = ''
+  for k, v of params
+    if v == '' then continue
+    if str != '' then str += '&'
+    str += "#{k}=#{v}"
+  setQueryString str