select标记美化--JS式插件、后期加载_表单特效

$.fn.extend({
    locate: function (x, y) {
        if (this.css("position") == "fixed") {
            y -= $(document).scrollTop();
        }
        return this.css({ left: x, top: y });
    },
    locateBeside: function (el, adjustX) {
        var p = $(el).offset(),
            w1 = $(el).outerWidth(),
            w2 = this.outerWidth(),
            h2 = this.outerHeight(),
            x = p.left + w1 + 5 + (adjustX || 0),
            y = p.top;
        if ($(document).width()             x = p.left - w2 - 5 - (adjustX || 0);
        }
        if ($(document).height()             y = p.top - (y + h2 + 15 - $(document).height());
        }
        return this.locate(x, y);
    },
    locateBelow: function (el, adjustY) {
        var p = $(el).offset();
        return this.locate(p.left, p.top + $(el).outerHeight() + 3 + (adjustY || 0));
    },
    locateCenter: function () {
        return this.locate(
            ($(window).width() - this.width()) / 2,
            ($(window).height() - this.height()) / 2 + $(document).scrollTop()
        );
    }
});