abortable-async.js

function abortableAsync(generator) {
  return ({
    [generator.name](...args) {
      let halt = false;
      try {
        return () => { halt = true; };
      } finally {
        (async() => {
          let g = generator.call(this, ...args);
          let value, done, err;
          while(!done && !halt) {
            if(err) {
              ({ value, done } = g.throw(err));
              err = null;
            } else {
              ({ value, done } = g.next(value));
            }
            if(value instanceof Promise) value = await value.catch(e => { err = e; });
          }
        })();
      }
    }
  })[generator.name];
}