ionic-framework/core/src/global/dom-controller.ts

/* tslint:disable */
export interface Now {
  (): number;
}

export interface DomController {
  read: DomControllerCallback;
  write: DomControllerCallback;
  raf: DomControllerCallback;
}

export interface RafCallback {
  (timeStamp: number): void;
}

export interface DomControllerCallback {
  (cb: RafCallback): void;
}

export function createDomControllerClient(win: Window, now: Now, rafPending?: boolean): DomController {
  const readCBs: RafCallback[] = [];
  const writeCBs: RafCallback[] = [];
  const raf = (cb: FrameRequestCallback): number => win.requestAnimationFrame(cb);


  function rafFlush(timeStamp: number, startTime?: number, cb?: RafCallback, err?: any) {
    try {
      startTime = now();

      // ******** DOM READS ****************
      while (cb = readCBs.shift()) {
        cb(timeStamp);
      }

      // ******** DOM WRITES ****************
      while (cb = writeCBs.shift()) {
        cb(timeStamp);

        if ((now() - startTime) > 8) {
          break;
        }
      }

    } catch (e) {
      err = e;
    }

    if (rafPending = (readCBs.length > 0 || writeCBs.length > 0)) {
      raf(rafFlush);
    }

    if (err) {
      console.error(err);
    }
  }

  return {

    read: (cb: RafCallback) => {
      readCBs.push(cb);

      if (!rafPending) {
        rafPending = true;
        raf(rafFlush);
      }
    },

    write: (cb: RafCallback) => {
      writeCBs.push(cb);

      if (!rafPending) {
        rafPending = true;
        raf(rafFlush);
      }
    },

    raf: raf
  };
}