Maybe not exactly what you are looking for, but I have been using my tapestryutil.js for some years with luck 😊
https://github.com/sveine/tapestry-multi-module-demo/blob/master/core/src/main/resources/META-INF/modules/util/tapestryutil.js A little demo: https://github.com/sveine/tapestry-multi-module-demo/blob/master/module1-root/module1/src/main/java/com/demo/module1/pages/AjaxDemo.java