See https://github.com/jenkinsci/js-samples. Doesn't have to be a Builder.

One of the goals with this is to show that js-modules only loads a single copy of a bundle i.e. will not load it again if it's already been loaded (i.e. it only gets "exported" once as in this unit test and this unit test).

To quote jglicks concern/query ....

... a scenario where an unbounded number of fragments from distinct plugins contributed to the initial page load, and several of those happen to require the same JS libs.