弹框随窗口变化始终居中

center($(".wrap_out"));

function center(obj) {
//obj这个参数是弹出框的整个对象
var screenWidth = $(window).width(), screenHeigth = $(window).height();
//获取屏幕宽高
var scollTop = $(document).scrollTop();
//当前窗口距离页面顶部的距离
var objLeft = (screenWidth - obj.width()) / 2;
///弹出框距离左侧距离
var objTop = (screenHeigth - obj.height()) / 3 + scollTop;
///弹出框距离顶部的距离
obj.css({
left:objLeft + "px",
top:objTop + "px"
});
//弹出框淡入
isOpen = 1;
//弹出框打开后这个变量置1 说明弹出框是打开装填
//当窗口大小发生改变时
$(window).resize(function() {
//只有isOpen状态下才执行
if (isOpen == 1) {
//重新获取数据
screenWidth = $(window).width();
screenHeigth = $(window).height();
var scollTop = $(document).scrollTop();
objLeft = (screenWidth - obj.width()) / 2;
var objTop = (screenHeigth - obj.height()) / 3 + scollTop;
obj.css({
left:objLeft + "px",
top:objTop + "px"
});

}
});
//当滚动条发生改变的时候
$(window).scroll(function() {
if (isOpen == 1) {
//重新获取数据
screenWidth = $(window).width();
screenHeigth = $(window).height();
var scollTop = $(document).scrollTop();
objLeft = (screenWidth - obj.width()) / 2;
var objTop = (screenHeigth - obj.height()) / 3 + scollTop;
obj.css({
left:objLeft + "px",
top:objTop + "px"
});
}
});
};