google.script.run while executing

Question

I am looking to show a spinner while a google script is running. How can one get the state to know if the script is running?

here is my code so far:

//I did this way so I can pass a variable to the run script function

   var somescript = "google.script.run.foo_"+bar+"()";

   var func = new Function (somescript);

   return(func());