Trying to make a progress bar

[mscteck]

Well hi.
I'm trying to make a progress bar using the edit-line command, but instead of modify the last line that was printed adds a new line or doesn't do anything. It surely is something im doing wrong, or i missunderstood the function of edit-line.
I've modified the code a lot, but this is the function that i have now:

let progressStatus = 0 /// to know if its the first time that executes or not
function progress(cmd){   /// the progress bar string is drawed outside and sent via cmd
  if(cmd === "done"){    /// if the progress bar finished
      progressStatus = 0  /// reset the status flag
  }   else{                         /// if not
     if(progressStatus === 0){     /// if its the first time that the function is executed
       Terminal.terminalObj.printToActive(cmd)   /// send the first line with printToActive
       progressStatus = 1;                                /// turns flag on
     } else{                                                         /// if its not the first time
       Terminal.terminalObj.runCommandOnActive(`edit-line ${cmd}`)  /// update the last line
     }
  }
}
//// The terminalObj is obtained inside the Terminal class with this
ref={(terminal) => { Terminal.terminalObj = terminal; }}

Any help will be apreciated.
Thanks.