Wait for input from dialog before proceeding in server code

I have a function in my server code(.gs) which pops up a dialog for input from user. I should wait for user input before proceeding with the function. To do this, I am using a while loop with sleep and checking for value of a key in PropertiesService. The value will be set on click of OK from the dialog.

Main.gs
function test(){
  DoSomething();
  SpreadsheetApp.getUi().showModalDialog(html, "Title");

  while(value is not set){
    Utilities.sleep(5000);
  }

  DoAnotherthing(value);
}

I am not happy with this solution (use of while and sleep) and was wondering if there is a better way to do this. Any pointers is appreciated.