var title = "xxxx";
var content = '<iframe scrolling="auto" frameborder="0" src="Purchase/PurchaseAdd.html" style="width:100%;height:100%;"></iframe>';
top.jQuery("#tabs").tabs('add', {
  title: title,
  content: content,
  closable: true,
  fit: true
});

注：#tabs是父Id，上面这段js代码写在子js文件里