object.groupby
An ESnext spec-compliant `Object.groupBy` shim/polyfill/replacement that works as far down as ES3.
object-replace-mustache
replace placeholders of an object with a view like you would use mustache.render for strings
pupa
Simple micro templating
mock-property
Given an object and a property, replaces a property descriptor (or deletes it), and returns a thunk to restore it.