如何根据数组值计算空闲可用时间

假设我有一个如下所示的数组：

{
    meeting: 'one',
    start_time: "07:15:00",
    end_time: "08:15:00"
},
{
    meeting: 'two',
    start_time: "15:45:00",
    end_time: "18:15:00"
}

现在我想计算从 00:00:00 到 24:00:00 的所有可用空闲时间。

例如新数组将如下所示：

{
    meeting: 'free time',
    start_time: "00:00:00",
    end_time: "07:14:00"
},
{
    meeting: 'one',
    start_time: "07:15:00",
    end_time: "08:15:00"
},
{
    meeting: 'free time',
    start_time: "08:16:00",
    end_time: "15:44:00"
},
{
    meeting: 'two',
    start_time: "15:45:00",
    end_time: "18:15:00"
}

关于如何在没有插件的情况下完成此任务有什么建议吗？

这就是我要做的 http://jsfiddle.net/cZUBk/4/:

function meeting(meeting, time1, time2) {
    this.meeting = meeting;
    this.start_time = time1;
    this.end_time = time2;
}


meeting.prototype.convert = function (a) {
    var b = this[a + '_time'];
    var start = b.slice(0, 3);
    var min = parseInt(b.slice(3, 5));
    min = a == "start" ? min - 1 : min + 1;
    min = min < 10 ? "0" + min : min;
    var ending = b.slice(5, 8);

    return start + min + ending

}

Array.prototype.getFreeTime = function () {
    var l = this.length,
        withFreeTime = [],
        i = 0;
    while (i < l) {

        var s = this[i - 1] ? this[i - 1].convert('end') : "00:00:00";
        withFreeTime.push(new meeting('freetime', s, this[i].convert('start')));
        withFreeTime.push(this[i]);
        i++;
    }

    //to add the freetime from "18:16:00" to  "23:59:00":
    withFreeTime.push(new meeting('freetime', this[i-1].convert('end'),'23:59:00'));

    return withFreeTime;
}

var meetings = [];
meetings[0] = new meeting('meeting1', "07:15:00", "08:15:00");
meetings[1] = new meeting('meeting2', "15:45:00", "18:15:00");
meetings = meetings.getFreeTime();
console.log(JSON.stringify(meetings));

控制台日志：

[{"meeting":"freetime","start_time":"00:00:00","end_time":"07:14:00"},
{"meeting":"meeting1","start_time":"07:15:00","end_time":"08:15:00"},
{"meeting":"freetime","start_time":"08:16:00","end_time":"15:44:00"},
{"meeting":"meeting2","start_time":"15:45:00","end_time":"18:15:00"},
{"meeting":"freetime","start_time":"18:16:00","end_time":"23:59:00"}]