The source code

    /**
     * @ignore
     *  abstract view for button
     * @author yiminghe@gmail.com
     */
    KISSY.add("button/buttonRender", function (S, Component) {
        // http://www.w3.org/TR/wai-aria-practices/
        return Component.Render.extend({
            createDom:function () {
                // set wai-aria role
                this.get("el")
                    .attr("role", "button");
            },
            _onSetChecked:function (v) {
                var self = this,
                    el = self.get("el"),
                    cls = self.getCssClassWithState("-checked");
                el[v ? 'addClass' : 'removeClass'](cls);
            },
            _onSetTooltip:function (title) {
                this.get("el").attr("title", title);
            },
            '_onSetDescribedby':function (describedby) {
                this.get("el").attr("aria-describedby", describedby);
            }
        }, {
            ATTRS:{
                describedby:{},
                tooltip:{},
                checked:{}
            }
        });
    }, {
        requires:['component/base']
    });