now = new Date(), hour = now.getHours()
if (hour < 6) {
    var hello = "凌晨好";
} else if (hour < 9) {
    var hello = "早上好";
} else if (hour < 12) {
    var hello = "上午好";
} else if (hour < 14) {
    var hello = "中午好";
} else if (hour < 17) {
    var hello = "下午好";
} else if (hour < 19) {
    var hello = "傍晚好";
} else if (hour < 22) {
    var hello = "晚上好";
} else {
    var hello = "夜深了";
}