Htmx patch for rhino not supporting ||=

Author: rbri

src/test/resources/libraries/htmx/htmx-1.9.1/src/htmx.js

@@ -1867,7 +1867,11 @@ return (function () {
 
         function addHxOnEventHandler(elt, eventName, code) {
             var nodeData = getInternalData(elt);
+            /* HtmlUnit patch
             nodeData.onHandlers ||= {};
+            */
+            if (!nodeData.onHandlers) nodeData.onHandlers = {};
+
             var func = new Function("event", code + "; return;");
             var listener = elt.addEventListener(eventName, function (e) {
                 return func.call(elt, e);