dijkstra

class State { 
  constructor() {
    this.nodes = {}
    this.subscribers= [] // array of function
  }
  
  AddNode(nodeName) { 
    this.nodes[nodeName] = {}
    this.emit()
  }

  AddRouteToNode(from, to, weight) { 
    this.nodes[from][to] = weight
    this.emit()
  }

  emit() { 
    for (const func of this.subscribers) {
      func(this.nodes)
    }
  }

  subscribe(func) { 
    this.subscribers.push(func)
  }
}

const state = new State()

class Canvas() { 
  constructor() { 
    state.subscribe(this.handleNewState)
    this.render()
  }

  handleNewState() { 
    this.render()
  }

  render() { 
    // do the thing
  }
}