Since JavaScript is single threaded, special techniques are necessary for asynchronous and reactive programming. Promises were introduced a few years ago to enable asynchronous programming without the dreaded "callback hell". They are a very powerful tool, especially with the async/await syntactic sugar. But limitations in promises opened the door to observables and their associated operator functions. They are much more powerful than promises overall, but can also be much more confusing. Signals are yet another approach, one that has gained a lot of attention since Angular adopted them in 2023, but it solves completely different problems. Now we have three different reactive primitives. Why? What's the difference between them? Why would you choose one over the other? Or will they all have complementary roles in a modern JavaScript/TypeScript application? Come to this session to get the answers to these questions, and more!