弹出窗口居中显示

$(function() {
// 居中
function center(obj) {
var screenWidth = $(window).width(), screenHeight = $(window).height(); //当前浏览器窗口的 宽高
var scrolltop = $(document).scrollTop();//获取当前窗口距离页面顶部高度
var objLeft = (screenWidth - obj.width())/2 ;
var objTop = (screenHeight - obj.height())/2 + scrolltop;

obj.css({left: objLeft + 'px', top: objTop + 'px'});

//浏览器窗口大小改变时
$(window).resize(function() {
screenWidth = $(window).width();
screenHeight = $(window).height();
scrolltop = $(document).scrollTop();

objLeft = (screenWidth - obj.width())/2 ;
objTop = (screenHeight - obj.height())/2 + scrolltop;

obj.css({left: objLeft + 'px', top: objTop + 'px'});

});

//浏览器有滚动条时的操作
$(window).scroll(function() {
screenWidth = $(window).width();
screenHeight = $(window).height();
scrolltop = $(document).scrollTop();

objLeft = (screenWidth - obj.width())/2 ;
objTop = (screenHeight - obj.height())/2 + scrolltop;

obj.css({left: objLeft + 'px', top: objTop + 'px'});
});

}

//点击显示
$('.wechat img').click(function() {
$('.mask , .bring').show();
center($('.bring'));
});

//隐藏的操作
$(".bring img").click(function(){
$(".mask , .bring").hide();
});

});