Monitor dism.exe from nodejs

Question

i need help to monitor the progressbar from dism.exe on windows systems. dism.exe is spawnd from my node.js script:

const { spawn, exec } = require('child_process');

const ls = exec('dism.exe /Unmount-Image /MountDir:"C:\\WinPE_amd64\\mount" /discard');

ls.stdout.on('data', (data) => {	
  console.log(`stdout: ${data}`);
});

ls.stderr.on('data', (data) => {
  console.log(`stderr: ${data}`);
});

ls.on('close', (code) => {
  console.log(`child process exited with code ${code}`);
});

The stdout on the terminal:

C:\Users\Admin\Desktop>node test.js stdout: Tool zur Imageverwaltung f�r die Bereitstellung Version: 10.0.17763.1

stdout: Bereitstellung des Abbilds wird aufgehoben

[= 2.0% ]

...

[===========================99.0%========================= ]

[==========================100.0%==========================]

stdout: Der Vorgang wurde erfolgreich beendet.

child process exited with code 0

C:\Users\Admin\Desktop>

I dont understand why the progressbar dont write to stdout/stderr. The "data" event is not fired when the progressbar is displayed/renderd

Can someone help me to get the progressbar passed as string in a cb/function?

Answer 1

The callback get's fired, but console.log did not work (i dont know exactly why, i think because the progressbard renders with in the same line \r and replace the text from console.log)

with util.insepct i get the exact output from dism. My callback:

                            const handleProgress = function handleProgress(str) {
								  
				
	str = util.inspect(str);
	
	if (str.substring(0, 4) == "'\\r[") {
                                  
                                  let precent = str.split("%")[0];
                                  precent = precent.replace(/=/g, "");
                                  precent = precent.substring(4);
                                  precent = Number(precent);
                                 
                                  console.log(precent);
                                  
                                    //console.log(">> done %d%%", precent);
                                    //socket.emit("installation.progress", precent);

                                } else {

                                    // normal "stat" feedback
									console.log("IN CB", str)

    }
		
                            };

And now it works, ;)