Boolean attributes now sync properly for radio buttons and checkboxes.

[escoberik]

Checkable inputs need the property "checked" to be settled to
true/false instead of the "value" attribute.

[gabetax]

Array#indexOf is not supported in IE8 and earlier. Given that backbone relies on underscore.js, you could instead rely on _.contains() (note the nativeIndexOf check):

  $.fn.isCheckable = function() {
    return _.contains(["checkbox", "radio"], this.attr("type"));
  };

Otherwise, 👍