Client-side js helper function for GETing

get.js

      function get(url, data, successCallback, errorCallback, responseType) {
        const urlObj = new URL(url);
        const params = urlObj.searchParams;
        Object.entries(data||{}).forEach(([key, value]) => params.set(key, value));
        url = urlObj.toString();
        fetch(url)
          .then(response => {
            if (!response.ok) { throw new Error(response.status); }
            const contentType = response.headers.get('content-type');
            const isJson = responseType === 'json' || (responseType === 'auto' && contentType && contentType.includes('application/json'));
            return isJson ? response.json() : response.text();
          })
          .then(result => successCallback(result))
          .catch(error => errorCallback(parseInt(error.message, 10) || 0));
      }