js 判断所选时间(或者当前时间)是否在某一时间段

[code]
var time_range = function (beginTime, endTime, nowTime) {
var strb = beginTime.split (":");
if (strb.length != 2) {
return false;
}

var stre = endTime.split (":");
if (stre.length != 2) {
return false;
}

var strn = nowTime.split (":");
if (stre.length != 2) {
return false;
}
var b = new Date ();
var e = new Date ();
var n = new Date ();

b.setHours (strb[0]);
b.setMinutes (strb[1]);
e.setHours (stre[0]);
e.setMinutes (stre[1]);
n.setHours (strn[0]);
n.setMinutes (strn[1]);

if (n.getTime () - b.getTime () > 0 && n.getTime () - e.getTime () < 0) {
return true;
} else {
alert ("当前时间是：" + n.getHours () + ":" + n.getMinutes () + "，不在该时间范围内！");
return false;
}
}
time_range ("21:30", "23:30", "3:22");
[/code]