Finite State Machines (FSM) & Hierarchical AI Architecture in Game Development

Hardcoding nested if/else statements for character actions (running, jumping, attacking, damaged) creates fragile spaghetti code where bugs multiply with every new feature. A **Finite State Machine (FSM)** encapsulates behavior into isolated state classes with formal transitions, entry hooks, and exit cleanup routines.

1. FSM State Pattern Implementation

// Modular State Interface & State Machine
class PlayerStateMachine {
  constructor(player) {
    this.player = player;
    this.currentState = null;
  }

  transitionTo(newState) {
    if (this.currentState) this.currentState.onExit();
    this.currentState = newState;
    this.currentState.onEnter();
  }

  update(delta) {
    if (this.currentState) this.currentState.onUpdate(delta);
  }
}