Javascript, run code after save

Hi!

We have the following code that runs when we click a button: 

function followUpTask(duration) {
debugger;
//check for not saved form

if (Xrm.Page.ui.getFormType() == 1 && followup == false) {
Xrm.Page.data.entity.save(true);
followupduration = duration;
followup = true;
return;
}
else if (Xrm.Page.data.entity.getIsDirty()) {

Xrm.Page.data.entity.save(true);
followupduration = duration;
followup = true;
return;
}

If the else if (Xrm.Page.data.entity.getIsDirty()) statement is true the form saves but following code

followupduration = duration;
followup = true;

will not run... We have to click the button once more for the code to run. Is there a way we can change this so the code runs after the form is saved?

Thanks for help!