AbortSignal.any() polyfill order POC

abortsignal-any-poc.js

<script>

let abortProto = AbortController.prototype;
let oldAbort = AbortController.prototype.abort;
   
Object.assign(abortProto, {
  abort(reason) {
    oldAbort.call(this, reason);
    if (this.signal.__dependents) {
      for (let controller of this.signal.__dependents) {
        controller.abort();
      }
    }
  }
});                              
                                 
AbortSignal.any = function(signals) {
  // ...after checking abort...
  const controller = new AbortController();
  const result = controller.signal;
  result.__sources = [];
  for (let signal of signals) {
    if (signal.__sources) {
      for (let source of signal.__sources) {
        if (!source.__dependents) {
          source.__dependents = [];
        }
        source.__dependents.push(controller);
        result.__sources.push(source);
      }                 
    } else {    
      if (!signal.__dependents) {
        signal.__dependents = [];
      }
      signal.__dependents.push(controller);
      result.__sources.push(signal);
    }
  }  
  return result;
};   

function run_test() {
  const controller = new AbortController();
  const signals = [];
  // The first event should be dispatched on the originating signal.
  signals.push(controller.signal);
  // All dependents are linked to `controller.signal` (never to another
  // composite signal), so this is the order events should fire.
  signals.push(AbortSignal.any([controller.signal]));
  signals.push(AbortSignal.any([controller.signal]));
  signals.push(AbortSignal.any([signals[0]]));
  signals.push(AbortSignal.any([signals[1]]));

  let result = "";
  for (let i = 0; i < signals.length; i++) {
    signals[i].addEventListener('abort', () => {
      result += i;
    });
  }
  controller.abort();
  // Should be "01234".
  console.log(result);
}

run_test();

</script>