Auto-reload of Template

This is a development-time convenience feature. When the server is run with productionMode = false, the framework listens for changes to used template files. When a change is discovered, the template is reparsed and the updated template tree is pushed to the browser for all active sessions, where it is immediately used to re-reender that part of the DOM.

[heruan]

I’m bumping this now since with ES modules in V14 the DX related to this pretty much collapsed.

In Bower mode, JRebel was able to push changed templates immediately and automatically; e.g.

• Project A (JAR): contains META-INF/resources/frontend/my-template.html
• Project B (WAR): depends on project A

Then running Project B with JRebel, a change in Project A’s my-template.html was immediately available in the browser.

With ES modules, this no longer applies (at least I’m not able to make it work); e.g.

• Project A (JAR): contains META-INF/resources/frontend/my-template.js
• Project B (WAR): depends on project A

Then running Project B with JRebel, a change in Project A’s my-template.js isn’t available in the browser and I need to restart the application… if I’m lucky, as 50% of the times I also need to rm -rf node_modules target in Project B root to avoid client errors such as:

Uncaught DOMException: Failed to execute 'define' on 'CustomElementRegistry': the name "dom-module" has already been used with this registry

I understand this is pretty old, but I hope it will be addressed ASAP now that V14 is released and since Vaadin’s suggesting to migrate to ES module I expect many are already facing this.

[joheriks]

Closing this ticket, as live reloading will now (in V17) trigger when any frontend resource is modified (and the main ticket covering monitoring submodule resources is #6347).