js中将两个日期字符串相减 获得天数

function dateDiff(date1, date2) {

            var type1 = typeof date1, type2 = typeof date2;

            if (type1 == 'string')

                date1 = stringToTime(date1);

            else if (date1.getTime)

                date1 = date1.getTime();

            if (type2 == 'string')

                date2 = stringToTime(date2);

            else if (date2.getTime)

                date2 = date2.getTime();

            //alert((date1 - date2) / (1000*60*60)); 

            return (date1 - date2) / (1000 * 60 * 60 * 24); //结果是小时 

        }

        //字符串转成Time(dateDiff)所需方法 

        function stringToTime(string) {

            var f = string.split(' ', 2);

            var d = (f[0] ? f[0] : '').split('-', 3);

            var t = (f[1] ? f[1] : '').split(':', 3);

            return (new Date(

           parseInt(d[0], 10) || null,

           (parseInt(d[1], 10) || 1) - 1,

            parseInt(d[2], 10) || null,

            parseInt(t[0], 10) || null,