fix(prop): Update attribute value when setting prop (#1579)

Fixes #883
Fixes #927
Fixes #1364

Author: fb55

lib/api/attributes.js

@@ -120,7 +120,11 @@ var getProp = function (el, name) {
 };
 
 var setProp = function (el, name, value) {
-  el[name] = rboolean.test(name) ? !!value : value;
+  if (name in el) {
+    el[name] = value;
+  } else {
+    setAttr(el, name, rboolean.test(name) ? (value ? '' : null) : value);
+  }
 };
 
 /**

test/api/attributes.js

@@ -172,6 +172,17 @@ describe('$(...)', function () {
       expect(checkbox.prop('checked')).to.equal(true);
     });
 
+    it('(key, value) : should update attribute', function () {
+      expect(checkbox.prop('checked')).to.equal(true);
+      expect(checkbox.attr('checked')).to.equal('checked');
+      checkbox.prop('checked', false);
+      expect(checkbox.prop('checked')).to.equal(false);
+      expect(checkbox.attr('checked')).to.equal(undefined);
+      checkbox.prop('checked', true);
+      expect(checkbox.prop('checked')).to.equal(true);
+      expect(checkbox.attr('checked')).to.equal('checked');
+    });
+
     it('(map) : object map should set multiple props', function () {
       checkbox.prop({
         id: 'check',