var time = "18:00:00".split(":");
var now = new Date();
time = new Date(now.getFullYear().now.getMonth().now.getDate(),time[0],time[1],time[2]);
//..............................
//然后把两个时间相减一下,得到相差的毫秒数,然后计算一下就行了。
//eg..
time = now - time;
hours = time % 24;/////////