Workaround for window.update on macOS?

I've been testing my new script application for JPEG export in Bridge. I'd like to have a progress indicator.

On Windows, I can use the window.update function to write a new value to a text field during the for loop where I actually export the files.

On macOS, I get a spinning rainbow (busy cursor) and the window isn't updated until the export is finished. Identical code.

An alert WILL interrupt the export loop on either platform and allow the window to update.

Any ideas? I'll post sample code later today.