dist/flow.js
function (isTest) {
      if (this.readState === 1) {
        return 'reading';
      } else if (this.pendingRetry || this.preprocessState === 1) {
        // if pending retry then that's effectively the same as actively uploading,
        // there might just be a slight delay before the retry starts
        return 'uploading';
      } else if (!this.xhr) {
        return 'pending';
      } else if (this.xhr.readyState < 4) {
        // Status is really 'OPENED', 'HEADERS_RECEIVED'
        // or 'LOADING' - meaning that stuff is happening
        return 'uploading';
      } else {
        if (this.flowObj.opts.successStatuses.indexOf(this.xhr.status) > -1) {
          // HTTP 200, perfect
		      // HTTP 202 Accepted - The request has been accepted for processing, but the processing has not been completed.
          return 'success';
        } else if (this.flowObj.opts.permanentErrors.indexOf(this.xhr.status) > -1 ||
            !isTest && this.retries >= this.flowObj.opts.maxChunkRetries) {
          // HTTP 413/415/500/501, permanent error
          return 'error';
        } else {
          // this should never happen, but we'll reset and queue a retry
          // a likely case for this would be 503 service unavailable
          this.abort();
          return 'pending';
        }
      }
    }
function (isTest) {
      if (this.readState === 1) {
        return 'reading';
      } else if (this.pendingRetry || this.preprocessState === 1) {
        // if pending retry then that's effectively the same as actively uploading,
        // there might just be a slight delay before the retry starts
        return 'uploading';
      } else if (!this.xhr) {
        return 'pending';
      } else if (this.xhr.readyState < 4) {
        // Status is really 'OPENED', 'HEADERS_RECEIVED'
        // or 'LOADING' - meaning that stuff is happening
        return 'uploading';
      } else {
        if (this.flowObj.opts.successStatuses.indexOf(this.xhr.status) > -1) {
          // HTTP 200, perfect
		      // HTTP 202 Accepted - The request has been accepted for processing, but the processing has not been completed.
          return 'success';
        } else if (this.flowObj.opts.permanentErrors.indexOf(this.xhr.status) > -1 ||
            !isTest && this.retries >= this.flowObj.opts.maxChunkRetries) {
          // HTTP 413/415/500/501, permanent error
          return 'error';
        } else {
          // this should never happen, but we'll reset and queue a retry
          // a likely case for this would be 503 service unavailable
          this.abort();
          return 'pending';
        }
      }
    }
Retrieve current chunk upload status
@function
@returns {string} 'pending', 'uploading', 'success', 'error'