function Nav(selector, data){
  this.ele = $(selector);
  this.init(data);
}

Nav.prototype.init = function(data){
  this.data = data || [];
  for(var i = 0; i<data.length ; i++){
    var item = data[i];
    var li = $("<li>");
    var a = $("<a>").appendTo(li);
    a.text(item.name);
    a.attr("href",item.href);
  	this.ele.append(li);
  }
}

Nav.prototype.updateData = function(){
	this.ele.find("li").remove();
  this.init(this.data);
}

var data = [{ name: "1", href:"#" }, { name: "2", href:"#" }];
var nav = new Nav(".nav", data);

data.push({name: "3", href: "#"});

nav.updateData();