[attr](http://james.padolsey.com/jquery/#v=1.10.2&fn=jQuery.attr) uses `setAttribute`, [prop](http://james.padolsey.com/jquery/#v=1.10.2&fn=jQuery.prop) sets using host methods (expando, like we're doing here). This line could be changed to mimic `attr` by doing:

```javascript
_.each(attr, function(val, name) {
  el.setAttribute(name, val);
});
```