var now = new Date();
timer = $.timer(timeout, function () {
    var sec_num = Math.ceil((now.getTime() - startTime.getTime()) / 1000);
    showPaperTimer(now, sec_num);
    if (sec_num % 60 == 0) {

    }
});

function showPaperTimer(now, sec_num) {
    var nowStr = now.getFullYear() + '-';
    nowStr += now.getMonth() + 1 + '-';
    nowStr += now.getDate() + ' ';
    nowStr += now.getHours() + ':';
    nowStr += now.getMinutes() + ':';
    nowStr += now.getSeconds();

    var hours = Math.floor(sec_num / 3600);
    var minutes = Math.floor((sec_num - (hours * 3600)) / 60);
    var seconds = sec_num - (hours * 3600) - (minutes * 60);
    if (hours < 10) { hours = "0" + hours; }
    if (minutes < 10) { minutes = "0" + minutes; }
    if (seconds < 10) { seconds = "0" + seconds; }
    var time0 = hours + ':' + minutes + ':' + seconds;

    $("#times").html("当前时间：" + str + "，已耗时：" + time0);
}

其中，$.timer是一个Jq时钟，来自于http://plugins.jquery.com/timer/，其常用操作有：

var timeout = 1000;
            var timer;
            $("input[name=start]").click(function() {
                $("#console").append("<span style=\"color: #0F0\">Timer started.</span<br />");
                timer = $.timer(timeout, function() {
                    $("#console").append("Timer completed.<br />");
                });
            });

            $("input[name=stop]").click(function() {
                if(timer.stop()) {
                    $("#console").append("<span style=\"color: #F00\">Timer stopped.</span<br />");
                }
            });

            $("input[name=pause]").click(function() {
                if(timer.pause()) {
                    $("#console").append("<span style=\"color: #FF0\">Timer paused.</span<br />");
                }
            });

            $("input[name=resume]").click(function() {
                if(timer.resume()) {
                    $("#console").append("<span style=\"color: #F00\">Timer resumed.</span<br />");
                }
            });
            $("input[name=reset]").click(function() {
                timer.stop();
                timeout = prompt("Reset timeout too:", 500);
                timer.reset(timeout);
                $("#console").append("<span style=\"color: #00F\">Timer reset.</span<br />");
            });

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