How to create a JQuery Clock / Timer

问题

I have a simple quiz application and I want display a nice timer / clock at the top of the page which shows the user how long they've been going for. (If I could somehow show them a timer for Total Quiz Time and also a second one for This Question Time that would be even cooler but I should be able to figure out how to do myself that once I've got one timer working.

My question is:

What's a nice, easy way to show a simple timer / clock using JQuery? (straight JS is also ok) I know how to check time, but how do I get incrementing seconds?

My own searches keep leading me to JQuery plugins (I want to roll my own) and also "event timers" which are not what I'm looking for...

回答1:

You're looking for the setInterval function, which runs a function every x milliseconds.

For example:

var start = new Date;

setInterval(function() {
    $('.Timer').text((new Date - start) / 1000 + " Seconds");
}, 1000);

回答2:

setInterval as suggested by SLaks was exactly what I needed to make my timer. (Thanks mate!)

Using setInterval and this great blog post I ended up creating the following function to display a timer inside my "box_header" div. I hope this helps anyone else with similar requirements!

 function get_elapsed_time_string(total_seconds) {
  function pretty_time_string(num) {
    return ( num < 10 ? "0" : "" ) + num;
  }

  var hours = Math.floor(total_seconds / 3600);
  total_seconds = total_seconds % 3600;

  var minutes = Math.floor(total_seconds / 60);
  total_seconds = total_seconds % 60;

  var seconds = Math.floor(total_seconds);

  // Pad the minutes and seconds with leading zeros, if required
  hours = pretty_time_string(hours);
  minutes = pretty_time_string(minutes);
  seconds = pretty_time_string(seconds);

  // Compose the string for display
  var currentTimeString = hours + ":" + minutes + ":" + seconds;

  return currentTimeString;
}

var elapsed_seconds = 0;
setInterval(function() {
  elapsed_seconds = elapsed_seconds + 1;
  $('#box_header').text(get_elapsed_time_string(elapsed_seconds));
}, 1000);

回答3:

################## JQuery (use API) #################   
 $(document).ready(function(){
         function getdate(){
                var today = new Date();
            var h = today.getHours();
            var m = today.getMinutes();
            var s = today.getSeconds();
             if(s<10){
                 s = "0"+s;
             }
             if (m < 10) {
                m = "0" + m;
            }
            $("h1").text(h+" : "+m+" : "+s);
             setTimeout(function(){getdate()}, 500);
            }

        $("button").click(getdate);
    });

################## HTML ###################
<button>start clock</button>
<h1></h1>

回答4:

How about the best of both worlds? I combined the answer with the OP's format.

function pretty_time_string(num) {
    return ( num < 10 ? "0" : "" ) + num;
  }

var start = new Date;    

setInterval(function() {
  var total_seconds = (new Date - start) / 1000;   

  var hours = Math.floor(total_seconds / 3600);
  total_seconds = total_seconds % 3600;

  var minutes = Math.floor(total_seconds / 60);
  total_seconds = total_seconds % 60;

  var seconds = Math.floor(total_seconds);

  hours = pretty_time_string(hours);
  minutes = pretty_time_string(minutes);
  seconds = pretty_time_string(seconds);

  var currentTimeString = hours + ":" + minutes + ":" + seconds;

  $('.timer').text(currentTimeString);
}, 1000);

回答5:

A 24 hour clock:

setInterval(function(){

        var currentTime = new Date();
        var hours = currentTime.getHours();
        var minutes = currentTime.getMinutes();
        var seconds = currentTime.getSeconds();

        // Add leading zeros
        minutes = (minutes < 10 ? "0" : "") + minutes;
        seconds = (seconds < 10 ? "0" : "") + seconds;
        hours = (hours < 10 ? "0" : "") + hours;

        // Compose the string for display
        var currentTimeString = hours + ":" + minutes + ":" + seconds;
        $(".clock").html(currentTimeString);

},1000);

// 24 hour clock  
setInterval(function() {

  var currentTime = new Date();
  var hours = currentTime.getHours();
  var minutes = currentTime.getMinutes();
  var seconds = currentTime.getSeconds();

  // Add leading zeros
  hours = (hours < 10 ? "0" : "") + hours;
  minutes = (minutes < 10 ? "0" : "") + minutes;
  seconds = (seconds < 10 ? "0" : "") + seconds;

  // Compose the string for display
  var currentTimeString = hours + ":" + minutes + ":" + seconds;
  $(".clock").html(currentTimeString);

}, 1000);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="clock"></div>

回答6:

If you can use jQuery with Moment.js (great library), this is the way:

var crClockInit1 = null;
var crClockInterval = null;
function crInitClock() {
    crClockInit1 = setInterval(function() {
        if (moment().format("SSS") <= 40) {
            clearInterval(crClockInit1);
            crStartClockNow();
        }
    }, 30);
}

function crStartClockNow() {
    crClockInterval = setInterval(function() {
        $('#clock').html(moment().format('D. MMMM YYYY H:mm:ss'));
    }, 1000);
}

Start clock initialization with crInitClock(). It's done this way to synchronize seconds. Without synchronization, you would start 1 second timer in half of second and it will be half second late after real time.

回答7:

var eventdate = new Date("January 01, 2014 00:00:00");

function toSt(n) {
 s=""
 if(n<10) s+="0"
 return s+n.toString();
}

function countdown() {
 cl=document.clock;
 d=new Date();
 count=Math.floor((eventdate.getTime()-d.getTime())/1000);
 if(count<=0)
   {cl.days.value ="----";
    cl.hours.value="--";
    cl.mins.value="--";
    cl.secs.value="--";
    return;
  }
 cl.secs.value=toSt(count%60);
 count=Math.floor(count/60);
 cl.mins.value=toSt(count%60);
 count=Math.floor(count/60);
 cl.hours.value=toSt(count%24);
 count=Math.floor(count/24);
 cl.days.value=count;    

 setTimeout("countdown()",500);
}

Hello, I've a similar assignment which involved creating a Javascript Countdown Clock. Here's the code I used. Plug the above code between the < script language="Javascript" >< /script > tags. Keep in mind that just having this javascript won't do much if you don't have the html to display the clock. I'll leave writing the html to you. Design the clock however you wish.

回答8:

    var timeInterval = 5;
    var blinkTime = 1;
    var open_signal = 'signal1';
    var total_signal = 1;

    $(document).ready(function () {
        for (var i = 1; i <= total_signal; i++) {
            var timer = (i == 1) ? timeInterval : (timeInterval * (i - 1));

            var str_html = '<div id="signal' + i + '">' +
                           '<span class="float_left">Signal ' + i + ' : </span>' +
                           '<div class="red float_left"></div>' +
                           '<div class="yellow float_left"></div>' +
                           '<div class="green float_left"></div>' +
                           '<div class="timer float_left">' + timer + '</div>' +
                           '<div style="clear: both;"></div>' +
                           '</div><div class="div_separate"></div>';

            $('.div_demo').append(str_html);
        }

        $('.div_demo .green').eq(0).css('background-color', 'green');
        $('.div_demo .red').css('background-color', 'red');
        $('.div_demo .red').eq(0).css('background-color', 'white');

        setInterval(function () {
            manageSignals();
        }, 1000);
    });

    function manageSignals() {
        var obj_timer = {};

        var temp_i = parseInt(open_signal.substr(6));
        if ($('#' + open_signal + ' .timer').html() == '0')
            open_signal = (temp_i == total_signal) ? 'signal1' : 'signal' + (temp_i + 1);

        for (var i = 1; i <= total_signal; i++) {
            var next_signal = (i == total_signal) ? 'signal1' : 'signal' + (i + 1);

            obj_timer['signal' + i] = parseInt($('#signal' + i + ' .timer').html()) - 1;

            if (obj_timer['signal' + i] == -1 && open_signal == next_signal && total_signal!=1) {
                obj_timer['signal' + i] = (timeInterval * (total_signal - 1)) - 1;

                $('#signal' + i + ' .red').css('background-color', 'red');
                $('#signal' + i + ' .yellow').css('background-color', 'white');
            }
            else if (obj_timer['signal' + i] == -1 && open_signal == 'signal' + i) {
                obj_timer['signal' + i] = (timeInterval - 1);

                $('#signal' + i + ' .red').css('background-color', 'white');
                $('#signal' + i + ' .yellow').css('background-color', 'white');
                $('#signal' + i + ' .green').css('background-color', 'green');
            }
            else if (obj_timer['signal' + i] == blinkTime && open_signal == 'signal' + i) {
                $('#signal' + i + ' .yellow').css('background-color', 'yellow');
                $('#signal' + i + ' .green').css('background-color', 'white');
            }

            $('#signal' + i + ' .timer').html(obj_timer['signal' + i]);
        }
    }
</script>

回答9:

Here's @SLaks answer, but in pure ES6 JavaScript.

var start = new Date,
  $timer = document.querySelector('.Timer');

setInterval(function(timestamp) {
    $timer.innerText = `${timestamp - start) / 1000} Seconds`;
}, 1000);

回答10:

var timeInterval = 5;
    var blinkTime = 1;
    var open_signal = 'top_left';

    $(document).ready(function () {
        $('#div_top_left .timer').html(timeInterval);
        $('#div_top_right .timer').html(timeInterval);
        $('#div_bottom_right .timer').html(timeInterval * 2);
        $('#div_bottom_left .timer').html(timeInterval * 3);

        $('#div_top_left .green').css('background-color', 'green');
        $('#div_top_right .red').css('background-color', 'red');
        $('#div_bottom_right .red').css('background-color', 'red');
        $('#div_bottom_left .red').css('background-color', 'red');

        setInterval(function () {
            manageSignals();
        }, 1000);
    });

    function manageSignals() {
        var top_left_time = parseInt($('#div_top_left .timer').html()) - 1;
        var top_right_time = parseInt($('#div_top_right .timer').html()) - 1;
        var bottom_left_time = parseInt($('#div_bottom_left .timer').html()) - 1;
        var bottom_right_time = parseInt($('#div_bottom_right .timer').html()) - 1;

        if (top_left_time == -1 && open_signal == 'top_left') open_signal = 'top_right';
        else if (top_right_time == -1 && open_signal == 'top_right') open_signal = 'bottom_right';
        else if (bottom_right_time == -1 && open_signal == 'bottom_right') open_signal = 'bottom_left';
        else if (bottom_left_time == -1 && open_signal == 'bottom_left') open_signal = 'top_left';

        if (top_left_time == -1) {
            if (open_signal == 'top_right') {
                top_left_time = (timeInterval * 3) - 1;
                $('#div_top_left .red').css('background-color', 'red');
                $('#div_top_left .yellow').css('background-color', 'white');
                $('#div_top_left .green').css('background-color', 'white');
            }
            else if (open_signal == 'top_left') {
                top_left_time = timeInterval - 1;
                $('#div_top_left .red').css('background-color', 'white');
                $('#div_top_left .yellow').css('background-color', 'white');
                $('#div_top_left .green').css('background-color', 'green');
            }
        }

        if (top_right_time == -1) {
            if (open_signal == 'bottom_right') {
                top_right_time = (timeInterval * 3) - 1;
                $('#div_top_right .red').css('background-color', 'red');
                $('#div_top_right .yellow').css('background-color', 'white');
                $('#div_top_right .green').css('background-color', 'white');
            }
            else if (open_signal == 'top_right') {
                top_right_time = timeInterval - 1;
                $('#div_top_right .red').css('background-color', 'white');
                $('#div_top_right .yellow').css('background-color', 'white');
                $('#div_top_right .green').css('background-color', 'green');
            }
        }

        if (bottom_right_time == -1) {
            if (open_signal == 'bottom_left') {
                bottom_right_time = (timeInterval * 3) - 1;
                $('#div_bottom_right .red').css('background-color', 'red');
                $('#div_bottom_right .yellow').css('background-color', 'white');
                $('#div_bottom_right .green').css('background-color', 'white');
            }
            else if (open_signal == 'bottom_right') {
                bottom_right_time = timeInterval - 1;
                $('#div_bottom_right .red').css('background-color', 'white');
                $('#div_bottom_right .yellow').css('background-color', 'white');
                $('#div_bottom_right .green').css('background-color', 'green');
            }
        }

        if (bottom_left_time == -1) {
            if (open_signal == 'top_left') {
                bottom_left_time = (timeInterval * 3) - 1;
                $('#div_bottom_left .red').css('background-color', 'red');
                $('#div_bottom_left .yellow').css('background-color', 'white');
                $('#div_bottom_left .green').css('background-color', 'white');
            }
            else if (open_signal == 'bottom_left') {
                bottom_left_time = timeInterval - 1;
                $('#div_bottom_left .red').css('background-color', 'white');
                $('#div_bottom_left .yellow').css('background-color', 'white');
                $('#div_bottom_left .green').css('background-color', 'green');
            }
        }

        if (top_left_time == blinkTime && open_signal == 'top_left') {
            $('#div_top_left .yellow').css('background-color', 'yellow');
            $('#div_top_left .green').css('background-color', 'white');
        }
        if (top_right_time == blinkTime && open_signal == 'top_right') {
            $('#div_top_right .yellow').css('background-color', 'yellow');
            $('#div_top_right .green').css('background-color', 'white');
        }
        if (bottom_left_time == blinkTime && open_signal == 'bottom_left') {
            $('#div_bottom_left .yellow').css('background-color', 'yellow');
            $('#div_bottom_left .green').css('background-color', 'white');
        }
        if (bottom_right_time == blinkTime && open_signal == 'bottom_right') {
            $('#div_bottom_right .yellow').css('background-color', 'yellow');
            $('#div_bottom_right .green').css('background-color', 'white');
        }

        $('#div_top_left .timer').html(top_left_time);
        $('#div_top_right .timer').html(top_right_time);
        $('#div_bottom_left .timer').html(bottom_left_time);
        $('#div_bottom_right .timer').html(bottom_right_time);
    }

来源：https://stackoverflow.com/questions/2604450/how-to-create-a-jquery-clock-timer