autoroll/modules/rpc/index.ts

import { AutoRollService, AutoRollServiceClient } from './rpc';

export * from './rpc';

const host = `${window.location.protocol}//${window.location.host}`;
let rpcClient: AutoRollService = new AutoRollServiceClient(
  host,
  window.fetch.bind(window)
);

/**
 * GetAutoRollService returns an AutoRollService implementation which dispatches
 * events indicating when requests have started and ended.
 *
 * @param ele The parent element, used to dispatch events.
 */
export function GetAutoRollService(ele: HTMLElement): AutoRollService {
  const handler = {
    get(target: any, propKey: any, receiver: any) {
      const origMethod = target[propKey];
      return function (...args: any[]) {
        ele.dispatchEvent(new CustomEvent('begin-task', { bubbles: true }));
        return origMethod
          .apply(rpcClient, args)
          .then((v: any) => {
            ele.dispatchEvent(new CustomEvent('end-task', { bubbles: true }));
            return v;
          })
          .catch((err: any) => {
            ele.dispatchEvent(
              new CustomEvent('fetch-error', {
                detail: {
                  error: err,
                  loading: propKey,
                },
                bubbles: true,
              })
            );
            Promise.reject(err);
          });
      };
    },
  };
  return new Proxy(rpcClient, handler);
}

/**
 * MockRPCsForTesting switches this module to use the given AutoRollService for
 * testing purposes.
 */
export function MockRPCsForTesting(repl: AutoRollService) {
  rpcClient = repl;
}