debug-audio-nodes.ts

interface State {
  index: number;
  name: string;
  createdAt: number;
  startedAt: number;
  stoppedAt: number;
  connectedAt: number;
  disconnectedAt: number;
}

const nodes = new WeakMap<AudioNode, State>();
const states = new Array<State>();

const DEBUG = false;

export function unwrapContext(audioContext: AudioContext): AudioContext {
  if (!DEBUG) {
    return audioContext;
  }
  return (audioContext as any).unsafeUnwrap || audioContext;
}
export function unwrapNode(audioNode: AudioNode): AudioNode {
  if (!DEBUG) {
    return audioNode;
  }
  return (audioNode as any).unsafeUnwrap || audioNode;
}

export function proxyContext(audioContext: AudioContext): AudioContext {
  if (!DEBUG) {
    return audioContext;
  }
  return new Proxy<AudioContext>(audioContext, {
    get: function(target: AudioContext, property: string) {
      if (property === "unsafeUnwrap") {
        return target;
      }
      var value = (target as any)[property];
      if (typeof value !== "function") {
        return value;
      }
      return function(...args: any[]) {
        if (!property.startsWith("create")) {
          return Reflect.apply(value, target, args);
        }
        const state: State = {
          index: states.length,
          name: property.slice(6),
          createdAt: target.currentTime,
          startedAt: null,
          stoppedAt: null,
          connectedAt: null,
          disconnectedAt: null
        };
        const node = Reflect.apply(value, target, args);
        nodes.set(node, state);
        states.push(state);
        return proxyNode(node);
      };
    }
  });
}
function proxyNode(node: AudioNode): AudioNode {
  return new Proxy<AudioNode>(node, {
    get: function(target: AudioNode, property: string) {
      if (property === "unsafeUnwrap") {
        return target;
      }
      var value = (target as any)[property];
      if (typeof value !== "function") {
        return value;
      }
      return function(...args: any[]) {
        if (property === "start") {
          nodes.get(target).startedAt = args[0] || target.context.currentTime;
        }
        if (property === "stop") {
          nodes.get(target).stoppedAt = args[0] || target.context.currentTime;
        }
        if (property === "connect") {
          nodes.get(target).connectedAt = target.context.currentTime;
          args = args.map(unwrapNode);
        }
        if (property === "disconnect") {
          nodes.get(target).disconnectedAt = target.context.currentTime;
          args = args.map(unwrapNode);
        }
        return Reflect.apply(value, target, args);
      };
    },
    set: function(target: AudioNode, property: string, value: any) {
      return ((target as any)[property] = value);
    }
  });
}

if (DEBUG) {
  (window as any).states = states;
  (window as any).showState = () => {
    states
      .map(
        (s, i) =>
          `    ${i}`.slice(-5) +
          ":" +
          `${s.createdAt}`.slice(-5) +
          " " +
          s.name.slice(0, 4) +
          " " +
          (s.connectedAt ? "[" : " ") +
          " " +
          (s.startedAt ? "<" : " ") +
          " " +
          (s.stoppedAt ? ">" : " ") +
          " " +
          (s.disconnectedAt ? "]" : " ")
      )
      .forEach(s => console.log(s));
  };
}