Fossil

           || payload instanceof Array)){
      payload = JSON.stringify(payload);
      opt.contentType = 'application/json';
    }
  }
  const url=[F.repoUrl(uri,opt.urlParams)],
        x=new XMLHttpRequest();
  if('POST'===opt.method && 'string'===typeof opt.contentType){
    x.setRequestHeader('Content-Type',opt.contentType);
  }
  if('json'===opt.responseType){
    /* 'json' is an extension to the supported XHR.responseType
       list. We use it as a flag to tell us to JSON.parse()
       the response. */
    jsonResponse = true;
    x.responseType = 'text';
  }else{

      opt.onload.apply(opt, args);
    }catch(e){
      opt.onerror(e);
    }
  };
  try{opt.beforesend()}catch(e){/*ignore*/}
  x.open(opt.method||'GET', url.join(''), true);
  if('POST'===opt.method && 'string'===typeof opt.contentType){
    x.setRequestHeader('Content-Type',opt.contentType);
  }
  x.timeout = +opt.timeout || f.timeout;
  if(undefined!==payload) x.send(payload);
  else x.send();
  return this;
};

window.fossil.fetch.beforesend = function(){};
window.fossil.fetch.aftersend = function(){};
window.fossil.fetch.timeout = 15000/* Default timeout, in ms. */;