Answers for "how to add a class to a created element before appending"

create element javascript with id

var btn = document.createElement('div'); 
btn.setAttribute("id", "div1");

javascript create element with class

Let suppose we are creating a div using javascript create element
// create a new div element 
	var newDiv = document.createElement("div"); 
// assigning class name to the new div
	newDiv.className = "className";