CRM Development- Javascript

Hi all,

I have a decimal field with precision zero, using javascript i have to increment this decimal value by 1 and the event is onSave and below is my code

function increament () {
var value = Xrm.Page.getAttribute("new_revisionid").getValue()
var isDirty = Xrm.Page.data.entity.getIsdirty ();
var finalvalue = null;
if (isDirty == True){
finalvalue = value++;
Xrm.Page.getAttribute("mew_revisionid").setValue("finalvalue");
}
}

But i receive the following error: "increment is not defined at eval"

I am not sure where this is going wrong, can anyone suggest me inputs here?