The source code

    /**
     * @ignore
     *  close extension for kissy dialog
     * @author yiminghe@gmail.com
     */
    KISSY.add("overlay/extension/close-render", function (S, Node) {

        var CLS_PREFIX = 'ext-';

        function getCloseRenderBtn(prefixCls) {
            return new Node("<a " +
                "tabindex='0' " +
                "href='javascript:void(\"关闭\")' " +
                "role='button' " +
                "style='z-index:9' " +
                "class='" + prefixCls + CLS_PREFIX + "close" + "'>" +
                "<span class='" +
                prefixCls + CLS_PREFIX + "close-x" +
                "'>关闭<" + "/span>" +
                "<" + "/a>");
        }

        function CloseRender() {
        }

        CloseRender.ATTRS = {
            closable: {
                value: true
            },
            closeBtn: {
            }
        };

        CloseRender.HTML_PARSER = {
            closeBtn: function (el) {
                return el.one("." + this.get('prefixCls') + CLS_PREFIX + 'close');
            }
        };

        CloseRender.prototype = {
            _onSetClosable: function (v) {
                var self = this,
                    btn = self.get("closeBtn");
                if (v) {
                    if (!btn) {
                        self.setInternal("closeBtn", btn = getCloseRenderBtn(self.get('prefixCls')));
                    }
                    self.get("el").prepend(btn);
                } else {
                    if (btn) {
                        btn.remove();
                    }
                }
            }
        };

        return CloseRender;

    }, {
        requires: ["node"]
    });