I've recently taken more interest in Backbone.js. Backbone is proven but not as trendy as it once was. I intend to learn more about it, but I don't want to become enamored by features and ways of approaching things that were later found to be anti-patterns. Would someone with more experience help me identify things in Backbone that have not aged well? Its method of classing? Things used from Underscore that are now provided in ES2015/2019?

Would appreciate any fair criticism so I know what kool aid to avoid :-)

Specifically, I'm wondering if Backbone is the only solution out there for its "Collections". Are there alternatives to track/signal on changes to a collection of models? Seemed like at one time all the rage was on Observable data structures, but now that has changed. Why?