xstate and other libraries like it implement Harel's statecharts, which are an extension of FMSs with different semantics and composability (a.k.a. "hierarchy",

xstate and other libraries like it implement Harel's statecharts, which are an extension of FMSs with different semantics and composability (a.k.a. "hierarchy", where machines can embed other machines), so the relationship with regular expressions may not be that useful. "Classic state diagrams require the creation of distinct nodes for every valid combination of parameters. For all but the simplest of systems, this can lead to a very large number of nodes and transitions between nodes (state and transition explosion), which reduces the readability of the state diagram." [1] "What's missing in the traditional state machines is the mechanism for factoring out the common behavior in order to share it across many states. UML state machines address exactly this shortcoming of the conventional FSMs. They provide a number of features for eliminating the repetitions so that the complexity of a UML state machine no longer explodes..." [2] -- 1: https://en.wikipedia.org/wiki/State_diagram#Harel_statechart https://en.wikipedia.org/wiki/State_diagram#Harel_statechart 2: https://en.wikipedia.org/wiki/UML_state_machine#UML_extensions_to_the_traditional_FSM_formalism https://en.wikipedia.org/wiki/UML_state_machine#UML_extensio...