jquery ajax retry workout

ajax_retry.js

// extends ajax
$.ajax = (($oldAjax) => {
  var df = $.Deferred();
  // on fail, retry by creating a new Ajax deferred
  function check(self, status) {
    console.log("check " + status + " => " + self.retries);
    const shouldRetry = status != 'success' && status != 'parsererror';
    if (shouldRetry && self.retries > 0) {
      setTimeout(() => {
        console.log("retry " + self.retries);
        $.ajax(self);
      }, self.retryInterval || 100);
    }
  }

  function failed(jqXHR, status, e) {
    if (this.retries - 1 <= 0) {
      // 재시도 횟수가 끝나면, 오류 보내기
      df.reject(KfError.convertKfError(jqXHR, this.url));
    } else {
      this.retries --;
      check(this, 'retry', this.retries);
    }
  }

  function done(res, textStatus, jqXHR) {
    if (!res.success) { // 200코드지만, 응답에 실패라면 오류로 처리
      if (this.retries - 1 <= 0) {
        df.reject(KfError.createResponseError(res, this.url));
      } else {
        this.retries --;
        check(this, 'retry', this.retries)
      }
    } else {
      df.resolve(res, textStatus, jqXHR);
    }
  }
  return function (settings) {
    console.log("==>" + settings.url);
    $oldAjax(settings)
      .fail(failed)
      .done(done);
    return df;
  };
})($.ajax);


function createRequest(url) {
  return $.ajax({
    type: 'GET',
    url: url,
    timeout: 2000,
    retries: 3,
    retryInterval: 1000
  });
}


// testing
$(async function () {
  try {
    let res = await createRequest(Rest.correctUrl('/auth/refresh'));
    console.log('ok res');
  } catch (e) {
    console.log('결국 error : ' + e.message);
    console.log(e);
  }
});