Is there a helper or a way to get the request object’s URL similar to razor’s ToGetUrl() in typescript/javascript?
Not exactly, there’s no Route definitions in TypeScript DTO, so you would just create the url by appending the name of the Request DTO to /json/reply/{RequestDto}
and adding any properties on the queryString, e.g:
import { combinePaths, nameof, appendQueryString } from 'servicestack-client';
let pathInfo = combinePaths(baseUrl, "json", "reply", nameof(requestDto));
let url = appendQueryString(pathInfo, requestDto);