B2G/gecko/browser/components/downloads/content/downloads.js
/**
   * Localized string representing the total size of completed downloads, for
   * example "1.5 MB" or "Unknown size".
   */
Localized string representing the total size of completed downloads, for
example "1.5 MB" or "Unknown size".
Localized string representing the total size of completed downloads for example " 1 . 5 MB " or " Unknown size " .
get _fileSizeText()
  {
    let fileSize = this.dataItem.maxBytes;
    if (fileSize < 0) {
      return DownloadsCommon.strings.sizeUnknown;
    }
    let [size, unit] = DownloadUtils.convertByteUnits(fileSize);
    return DownloadsCommon.strings.sizeWithUnits(size, unit);
  }
get _fileSizeText ( ) { let fileSize = this . dataItem . maxBytes ; if ( fileSize < 0 ) { return DownloadsCommon . strings . sizeUnknown ; } let [ size , unit ] = DownloadUtils . convertByteUnits ( fileSize ) ; return DownloadsCommon . strings . sizeWithUnits ( size , unit ) ; }
Localized string representing the total size of completed downloads, for
 example "1.5 MB" or "Unknown size".
Localized string representing the total size of completed downloads for example " 1 . 5 MB " or " Unknown size " .
// Display the file size, but show "Unknown" for negative sizes.