Describe the states and allowed transitions of a program using a flowchart-like syntax. Switch to states directly, or by wiring-up events. Statebot is an FSM.
Define paths + routes without the repetition.
A tiny pattern-matching library in the style of the TC39 proposal
Apportion objects / arrays into multiple buckets based on predicates / patterns
Find DOM elements using an expressive query syntax, extract text and monitor changes.