Function patchThen

packages/zone.js/lib/common/promise.ts:589–610

(Ctor: Function)

    const symbolThenPatched = __symbol__('thenPatched');

    function patchThen(Ctor: Function) {
      const proto = Ctor.prototype;

      const prop = ObjectGetOwnPropertyDescriptor(proto, 'then');
      if (prop && (prop.writable === false || !prop.configurable)) {
        // check Ctor.prototype.then propertyDescriptor is writable or not
        // in meteor env, writable is false, we should ignore such case
        return;
      }

      const originalThen = proto.then;
      // Keep a reference to the original method.
      proto[symbolThen] = originalThen;

      Ctor.prototype.then = function (onResolve: any, onReject: any) {
        const wrapped = new ZoneAwarePromise((resolve, reject) => {
          originalThen.call(this, resolve, reject);
        });
        return wrapped.then(onResolve, onReject);
      };
      (Ctor as any)[symbolThenPatched] = true;
    }

    api.patchThen = patchThen;