Develop Reference

Stopwatch not incrementing JavaScript

I made a simple clock and used a button to switch to a stopwatch. Since I couldn't figure out a better solution I duplicated the container, asigned a function that toggles display on/off on the containers to swap between the clock and stopwatch so that it remains in the same position. I don't understand why my stopwatch is not incrementing and what I should do to solve this problem. Any help would be appreciated. Here's my code:
<div id="container">
<div id="clock">
<span id="back">88:88:88</span>
<span id="front">00:00:00</span>
<div class="buttons">
<button id="button-left" onclick="myFunction()"><i class="fas fa-stopwatch"></i></button>
<button id="button-stop"><i class="fa-solid fa-stop"></i></button>
<button id="button-play" ><i class="fa-solid fa-play"></i></button>
<button id="button-right"><i class="fa-solid fa-delete-left"></i></button>
</div>
</div>
</div>
<div id="container-2">
<div id="clock-2">
<span id="back-2">88:88:88</span>
<span id="front-2">00:00:00</span>
<div class="buttons-2">
<button id="button-left-2" onclick="myFunction()"><i class="fas fa-stopwatch"></i></button>
<button id="button-stop-2" onclick="stopSW()"><i class="fa-solid fa-stop"></i></button>
<button id="button-play-2" onclick="startSW()"><i class="fa-solid fa-play"></i></button>
<button id="button-right-2" onclick="reset()"><i class="fa-solid fa-delete-left"></i></button>
</div>
</div>
</div>
function myFunction() {
var x = document.getElementById("container-2");
let y = document.getElementById("container");
if (x.style.display === "none") {
x.style.display = "block";
y.style.display = "none";
} else {
x.style.display = "none";
y.style.display = "block";
}
}
function startSW() {
clearInterval(stopwatch);
start = setInterval(stopwatch, 1000);
}
function stopSW() {
clearInterval(start);
}
function reset(){
clearInterval(stopwatch);
document.getElementById("front-2").innerHTML = "00:00:00";
}
function stopwatch() {
let hours = 0;
let minutes = 0;
let seconds = 0;
let displayHours = 0;
let displayMinutes = 0;
let displaySeconds = 0;
seconds++;
if(seconds == 60){
seconds = 0;
minutes++;
if(minutes == 60) {
minutes = 0;
hours++;
}
}
if (seconds < 10){
displaySeconds = "0" + seconds;
} else {
displaySeconds = seconds;
}
if (minutes < 10){
displayMinutes = "0" + minutes;
} else {
displayMinutes = minutes;
}
if (hours < 10){
displayHours = "0" + hours;
} else {
displayHours = hours;
}
let stopwatchNow = displayHours + ":" + displayMinutes + ":" + displaySeconds;
document.getElementById("front-2").innerHTML = stopwatchNow;
}

Hello at the start of your stopwatch function you set
let hours = 0;
let minutes = 0;
let seconds = 0;
let displayHours = 0;
let displayMinutes = 0;
let displaySeconds = 0;
and that's what you display later in the code, you need to define this variables outside of this function

This is because in function stopwatch, every time this function runs you set
let hours = 0;
let minutes = 0;
let seconds = 0;
let displayHours = 0;
let displayMinutes = 0;
let displaySeconds = 0;
These variables will always be 0, since you set them when function runs. In order to fix this, you need to move them outside the function:
let hours = 0;
let minutes = 0;
let seconds = 0;
let displayHours = 0;
let displayMinutes = 0;
let displaySeconds = 0;
function stopwatch(){
// removed
seconds++; // this stays here
// the rest of your code goes in here
}
This way your variables won't reset to 0 when function starts to run

<div id="container-2">
<div id="clock-2">
<span id="front-2">00:00:00</span>
--- >>
<span id="back-2">88:88:88</span>
</div>
</div>
<div class="buttons-2">
<button id="button-left-2" onclick="myFunction()"><i class="fas fa-stopwatch"></i>fun</button>
<button id="button-stop-2" onclick="stopSW()"><i class="fa-solid fa-stop"></i>stop</button>
<button id="button-play-2" onclick="startSW()"><i class="fa-solid fa-play"></i>start</button>
<button id="button-right-2" onclick="reset()"><i class="fa-solid fa-delete-left"></i>reset</button>
</div>
<script>
function myFunction() {
var node = document.getElementById("back-2");
display(node);
}
var start;
function startSW() {
clearInterval(start);
start = setInterval(stopwatch, 1000);
}
function stopSW() {
clearInterval(start);
}
function reset(){
clearInterval(start);
document.getElementById("front-2").innerHTML = "00:00:00";
document.getElementById("back-2").innerHTML = "00:00:00";
hours = 0;
minutes = 0;
seconds = 0;
}
var hours = 0;
var minutes = 0;
var seconds = 0;
function stopwatch() {console.log('stopwatch')
seconds++;
if(seconds == 60){
seconds = 0;
minutes++;
if(minutes == 60) {
minutes = 0;
hours++;
}
}
display();
}
function display(node){
let displayHours = 0;
let displayMinutes = 0;
let displaySeconds = 0;
if (seconds < 10){
displaySeconds = "0" + seconds;
} else {
displaySeconds = seconds;
}
if (minutes < 10){
displayMinutes = "0" + minutes;
} else {
displayMinutes = minutes;
}
if (hours < 10){
displayHours = "0" + hours;
} else {
displayHours = hours;
}
let stopwatchNow = displayHours + ":" + displayMinutes + ":" + displaySeconds;
if(!node)node=document.getElementById("front-2");
node.innerHTML = stopwatchNow;
}
</script>
there were a variety of mistakes,
clearInterval not being given the correct value
the time variables needed to be declared in global scope
i can only guess what myfunction is supposed to be doing
etc...
have fun

Javascript stopwatch want the clock element to be a div not an input

So I have the following code, As you can see in the HTML I have a div with id=clock and an input element also with id=clock, basically if i remove the div or comment it out, the input element works fine, on the html page the clock in the input element will display the time, I would prefer it to use the div element for styling purposes; however, if i comment out the input element and use the div it does not count up, I think I understand why but I cant seem to fix it. Can someone help explain how I can do this using the following code?
var flagclock = 0;
var flagstop = 0;
var stoptime = 0;
var splitcounter = 0;
var currenttime;
var splitdate = '';
var output;
var clock;
// Start-Stop Function
function startstop() {
var startstop = document.getElementById('startstopbutton');
var startdate = new Date();
var starttime = startdate.getTime();
if (flagclock == 0) {
startstop.value = 'Stop';
flagclock = 1;
counter(starttime);
} else {
startstop.value = 'Start';
flagclock = 0;
flagstop = 1;
splitdate = '';
}
}
//Increment function
function counter(starttime) {
output = document.getElementById('output');
clock = document.getElementById('clock');
currenttime = new Date();
var timediff = currenttime.getTime() - starttime;
if (flagstop == 1) {
timediff = timediff + stoptime
}
if (flagclock == 1) {
clock.value = formattime(timediff, '');
refresh = setTimeout('counter(' + starttime + ');', 10);
} else {
window.clearTimeout(refresh);
stoptime = timediff;
}
}
function formattime(rawtime, roundtype) {
if (roundtype == 'round') {
var ds = Math.round(rawtime / 100) + '';
} else {
var ds = Math.floor(rawtime / 100) + '';
}
var sec = Math.floor(rawtime / 1000);
var min = Math.floor(rawtime / 60000);
ds = ds.charAt(ds.length - 1);
if (min >= 60) {
startstop();
}
sec = sec - 60 * min + '';
if (sec.charAt(sec.length - 2) != '') {
sec = sec.charAt(sec.length - 2) + sec.charAt(sec.length - 1);
} else {
sec = 0 + sec.charAt(sec.length - 1);
}
min = min + '';
if (min.charAt(min.length - 2) != '') {
min = min.charAt(min.length - 2) + min.charAt(min.length - 1);
} else {
min = 0 + min.charAt(min.length - 1);
}
return min + ':' + sec + ':' + ds;
}
// reset function
function resetclock() {
flagstop = 0;
stoptime = 0;
splitdate = '';
window.clearTimeout(refresh);
output.value = '';
splitcounter = 0;
if (flagclock == 1) {
var resetdate = new Date();
var resettime = resetdate.getTime();
counter(resettime);
} else {
clock.value = "00:00:0";
}
}
//Split function
function splittime() {
if (flagclock == 1) {
if (splitdate != '') {
var splitold = splitdate.split(':');
var splitnow = clock.value.split(':');
var numbers = new Array();
var i = 0
for (i; i < splitold.length; i++) {
numbers[i] = new Array();
numbers[i][0] = splitold[i] * 1;
numbers[i][1] = splitnow[i] * 1;
}
if (numbers[1][1] < numbers[1][0]) {
numbers[1][1] += 60;
numbers[0][1] -= 1;
}
if (numbers[2][1] < numbers[2][0]) {
numbers[2][1] += 10;
numbers[1][1] -= 1;
}
var mzeros = (numbers[0][1] - numbers[0][0]) < 10 ? '0' : '';
var szeros = (numbers[1][1] - numbers[1][0]) < 10 ? '0' : '';
output.value += '\t+' + mzeros + (numbers[0][1] - numbers[0][0]) + ':' + szeros + (numbers[1][1] - numbers[1][0]) + ':' + (numbers[2][1] - numbers[2][0]) + '\n';
}
splitdate = clock.value;
output.value += (++splitcounter) + '. ' + clock.value + '\n';
}
}
<input id="startstopbutton" class="buttonZ" style="width: 120px;" type="button" name="btn" id='btn' value="Start" onclick="startstop()" ;>
<input id="resetbutton" class="buttonZ" style="width: 120px;" type="button" name="btnRst1" id='btnRst1' value="Reset" onclick="resetclock()" ;>
<div id="clock" class="timerClock">00:00:00</div><br>
<!-- Clock 2 -->
<input id="clock" class="timerClock" type="text" value="00:00:0" style="text-align: center;" readonly=""><br>
<!-- Split Button -->
<input id="splitbutton" class="buttonZ" style="width: 120px; margin-right: 170px" type="button" value="Split Time" onclick="splittime();">
<!-- output for split times -->
<textarea id="output" spellcheck="false"></textarea>

You are using clock.value to set the contents of the <input> element. This will not work for <div> elements; you will need to use innerHTML instead:
clock = document.getElementById('clock'); //div#clock
// ...
clock.innerHTML = formattime(timediff, '');

have a div with id=clock and an input element also with id=clock,
This is bad. ID have to be UNIQUE. This is why when you have both present ( with same id ) the counter doesn't work. It selects just the first element with id clock which is the div.
It doesn't select the input. As you can see getElementById is singular. If you want to select both of them, add a common class and select that with getElementsByClassName(className) ( notice the plural Elements compared to Element from the ID selector ) or querySelectorAll(className) and loop through them.
I added clock-div as the id on the div
Also. div element does not have a value attribute ( unlike input ). To get or edit/manipulate the text inside a div element you should use div.innerText instead of div.value. As a side note, div can have HTML inside it (input can't) . You can access it with div.innerHTML
So basically you need to change the id of the div ( if you also want to keep the input ) and change clock.value to clock.innerText everywhere.
Another option would be to keep both input and div. And assign the value of the input to the div.innerText.
var flagclock = 0;
var flagstop = 0;
var stoptime = 0;
var splitcounter = 0;
var currenttime;
var splitdate = '';
var output;
var clock;
// Start-Stop Function
function startstop() {
var startstop = document.getElementById('startstopbutton');
var startdate = new Date();
var starttime = startdate.getTime();
if (flagclock == 0) {
startstop.value = 'Stop';
flagclock = 1;
counter(starttime);
} else {
startstop.value = 'Start';
flagclock = 0;
flagstop = 1;
splitdate = '';
}
}
//Increment function
function counter(starttime) {
output = document.getElementById('output');
// change here id
clock = document.getElementById('clock-div');
currenttime = new Date();
var timediff = currenttime.getTime() - starttime;
if (flagstop == 1) {
timediff = timediff + stoptime
}
if (flagclock == 1) {
clock.innerText = formattime(timediff, '');
refresh = setTimeout('counter(' + starttime + ');', 10);
} else {
window.clearTimeout(refresh);
stoptime = timediff;
}
}
function formattime(rawtime, roundtype) {
if (roundtype == 'round') {
var ds = Math.round(rawtime / 100) + '';
} else {
var ds = Math.floor(rawtime / 100) + '';
}
var sec = Math.floor(rawtime / 1000);
var min = Math.floor(rawtime / 60000);
ds = ds.charAt(ds.length - 1);
if (min >= 60) {
startstop();
}
sec = sec - 60 * min + '';
if (sec.charAt(sec.length - 2) != '') {
sec = sec.charAt(sec.length - 2) + sec.charAt(sec.length - 1);
} else {
sec = 0 + sec.charAt(sec.length - 1);
}
min = min + '';
if (min.charAt(min.length - 2) != '') {
min = min.charAt(min.length - 2) + min.charAt(min.length - 1);
} else {
min = 0 + min.charAt(min.length - 1);
}
return min + ':' + sec + ':' + ds;
}
// reset function
function resetclock() {
flagstop = 0;
stoptime = 0;
splitdate = '';
window.clearTimeout(refresh);
output.value = '';
splitcounter = 0;
if (flagclock == 1) {
var resetdate = new Date();
var resettime = resetdate.getTime();
counter(resettime);
} else {
clock.innerText = "00:00:0";
}
}
//Split function
function splittime() {
if (flagclock == 1) {
if (splitdate != '') {
var splitold = splitdate.split(':');
var splitnow = clock.value.split(':');
var numbers = new Array();
var i = 0
for (i; i < splitold.length; i++) {
numbers[i] = new Array();
numbers[i][0] = splitold[i] * 1;
numbers[i][1] = splitnow[i] * 1;
}
if (numbers[1][1] < numbers[1][0]) {
numbers[1][1] += 60;
numbers[0][1] -= 1;
}
if (numbers[2][1] < numbers[2][0]) {
numbers[2][1] += 10;
numbers[1][1] -= 1;
}
var mzeros = (numbers[0][1] - numbers[0][0]) < 10 ? '0' : '';
var szeros = (numbers[1][1] - numbers[1][0]) < 10 ? '0' : '';
output.value += '\t+' + mzeros + (numbers[0][1] - numbers[0][0]) + ':' + szeros + (numbers[1][1] - numbers[1][0]) + ':' + (numbers[2][1] - numbers[2][0]) + '\n';
}
splitdate = clock.innerText;
output.innerText += (++splitcounter) + '. ' + clock.value + '\n';
}
}
<input id="startstopbutton" class="buttonZ" style="width: 120px;" type="button" name="btn" id='btn' value="Start" onclick="startstop()" ;>
<input id="resetbutton" class="buttonZ" style="width: 120px;" type="button" name="btnRst1" id='btnRst1' value="Reset" onclick="resetclock()" ;>
<div id="clock-div" class="timerClock">00:00:00</div><br>
<!-- Clock 2 -->
<input id="clock" class="timerClock" type="text" value="00:00:0" style="text-align: center;" readonly=""><br>
<!-- Split Button -->
<input id="splitbutton" class="buttonZ" style="width: 120px; margin-right: 170px" type="button" value="Split Time" onclick="splittime();">
<!-- output for split times -->
<textarea id="output" spellcheck="false"></textarea>

return to zero after reach max value and add the remaining value javascript

sorry i am newbie here
i need some help,
this case like notice a time.
when real time passes input value, then span with id alertLabel will change.
the problem is, if input value plus with input with id Duration will exceed real minutes or hours.
this is my code example.
javascript.js
var alertLabel = document.getElementById("alertLabel");
var less = document.getElementById("lessThan").value.replace(":", "");
var late = document.getElementById("timeIn").value.replace(":", "");
var duration = parseInt(document.getElementById("Duration").value);
var outs = document.getElementById("timesOut").value.replace(":", "");
var lessInt = parseInt(less);
var lateInt = parseInt(late);
var outsInt = parseInt(outs);
var durationOut = outsInt + duration; // this will be exceed
var durationIn = lateInt + duration; // this will be exceed
function getAlert() {
let times = new Date();
let sh = times.getHours() + "";
let sm = times.getMinutes() + "";
let ss = times.getSeconds() + "";
let shLong = sh.length == 1 ? "0" + sh : sh;
let smLong = sm.length == 1 ? "0" + sm : sm;
let ssLong = ss.length == 1 ? "0" + ss : ss;
let shSm = shLong + smLong;
document.getElementById("clock").innerHTML = shLong + ":" + smLong + ":" + ssLong;
if (shSm >= outsInt && shSm < durationOut) {
alertLabel.innerHTML = "OUT!!";
} else if (shSm >= lessInt && shSm < lateInt) {
alertLabel.innerHTML = "hurry up, don't be late!!";
} else if (shSm >= lateInt && shSm < durationIn) {
alertLabel.innerHTML = "LATE!!";
} else {
if (shLong >= 21 || shLong <= 4) {
alertLabel.innerHTML = "good dream tonight !!";
} else if (shLong >= 5 && shLong <= 11) {
alertLabel.innerHTML = "spirit Morning !!";
} else if (shLong >= 12 && shLong <= 17) {
alertLabel.innerHTML = "happy Noon !!";
} else if (shLong >= 18 && shLong <= 20) {
alertLabel.innerHTML = "nice evening !!";
}
}
}
<!doctype html>
<html>
<head>
<title></title>
</head>
<body onload="getAlert();setInterval('getAlert()',1000)">
<span id="clock"></span>
<span id="alertLabel"></span>
<div></div>
<input class="" type="text" id="lessThan" value="13:45" name="lessThan"> <!-- when time to in is near -->
<input class="" type="text" id="timeIn" value="13:48" name="timeIn"> <!-- time in and get alert Late -->
<input type="text" id="timesOut" value="13:55" name="timesOut"> <!-- value time to out and get alert Out -->
<input type="text" name="Duration" id="Duration" value="5"> <!-- duration alert for id timeIn and timesOut if more than 100 is the problem, this input as minute -->
</body>
</html>
this is my last try, example in input id timeIn
var a = document.getElementById("timeIn").value.split(":");
for (var i = 0; i < duration; i++){
var b = parseInt(a[0]); // this for hours
var c = parseInt(a[1]); // this for minutes
var x = c + i;
if (x >= 60){
var n = b + 1;
x = x-60;
}
console.log(x);
}
in my last try, in log var x return to zero just once
and the question is, if input value with id duration more than 100, how looping, if each var x reach value (60) his return to zero and var c plus 1 each var x reach 60.
maybe anyone have an easier one to solve this case.
sorry if the explanation is unclear.

How to get child arrays in ajax html()

I have a form for my array of data will print to view with html() and this data each one has child array, I need to get data of those child arrays in my html() as well
Screenshots
my data
how it will look
# Code
HTML
<div class="answerPanel"></div>
<button id="clicks" class="btn btn-primary">Begin</button>
Script
var index = 0;
$("#clicks").click(function(){
// timer function
function timer(seconds, countdownTimer, callback) {
var days = Math.floor(seconds / 24 / 60 / 60);
var hoursLeft = Math.floor((seconds) - (days * 86400));
var hours = Math.floor(hoursLeft / 3600);
var minutesLeft = Math.floor((hoursLeft) - (hours * 3600));
var minutes = Math.floor(minutesLeft / 60);
var remainingSeconds = seconds % 60;
if (remainingSeconds < 10) {
remainingSeconds = "0" + remainingSeconds;
}
document.getElementById('countdown').innerHTML = hours + ":" + minutes + ":" + remainingSeconds;
if (seconds == 0) {
clearInterval(countdownTimer);
document.getElementById('countdown').innerHTML = "Times Up!";
$("#clicks").attr("disabled", true);
$('.answerPanel').html('<div class="text-center text-danger">OH NO! <br> Times Up!</div>');
} else {
seconds--;
}
//Pass seconds param back to the caller.
callback(seconds);
}
//We pass the countdownTimer param into the timer function as well.
var countdownTimer = null,
seconds = data.quizzes[index].quiz_time;
countdownTimer = setInterval(function() {
timer(seconds, countdownTimer, function(_seconds){
seconds = _seconds;
})
}, 1000);
// printing function
if(typeof data.quizzes[index] != 'undefined'){
var row = `<form>
<div class="row">
<div class="col-md-12">
<div class="pull-left questionTitle">
${data.quizzes[index].question}
</div>
<div class="pull-right" id="countdown"></div>
</div>
<div class="col-md-12">
Choice 1
</div>
<div class="col-md-12">
Choice 2
</div>
<div class="col-md-12">
Choice (etc.)
</div>
</div>
</form>`;
$('.answerPanel').html(row);
index++;
}
if(data.quizzes.length > index+1) {
$("#clicks").html("Next");
}
if(data.quizzes.length === index) {
$("#clicks").html("Finish");
}
//end of printing function
});
Any idea?

Please see my code below
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<body id="banner">
<ul id="eventCal">
</ul>
<button id="clicks">Click</button>
<script type="text/javascript">
jQuery(document).ready(function($){
var quizzes = [{title:'title1',choices:[{choice:'choice1'},{choice:'choice2'}]},
{title:'title2',choices:[{choice:'new1'},{choice:'new2'}]},
{title:'title3',choices:[{choice:'demo1'},{choice:'demo2'}]}];
var index = 0;
//console.log(quizzes.length)
$("#clicks").click(function(){
if(typeof quizzes[index] != 'undefined'){
var html = '<li><span>'+quizzes[index].title+'</span></li>';
if(quizzes[index].choices.length > 0){
html+='<li class="choises">';
quizzes[index].choices.forEach((element, index, array) => {
//console.log(element.title);
html+='<ul>';
html+='<li><span>'+element.choice+'</span></li>';
html+='</ul>';
});
html+='</li>';
}
$("#eventCal").html(html);
index++;
}
if(quizzes.length === index)
$("#clicks").html("Finish");
})
});
</script>
</body>

Inside of row, you can get the choices by:
let choices = quizzes[index].choices

Timer not accurate [duplicate]

This question already has answers here:
How to create an accurate timer in javascript?
(15 answers)
Closed 6 years ago.
I am building an activity timer, but the code I have is not working properly. The timer is going ~40% faster than real time. What's going wrong?
var sec = 00;
var min = 00;
var hr = 00;
var t;
var timer_is_on = 0;
function timedCount() {
if (min == 0) {
min = 1;
}
document.getElementById('seconds').value = sec;
document.getElementById('minutes').value = min;
$('.node-form .form-item:nth-child(4) input').val(min);
document.getElementById('hours').value = hr;
$('.node-form .form-item:nth-child(3) input').val(hr);
sec = sec + 1;
if (sec == 60) {
sec = 0;
min = min + 1;
if (min == 60) {
min = 1;
hr = hr + 1;
}
}
t = setTimeout("timedCount()", 1000);
}
function doTimer() {
if (!timer_is_on) {
timer_is_on = 1;
timedCount();
}
}
function stopCount() {
clearTimeout(t);
timer_is_on = 0;
}
function resetCount() {
stopCount();
sec = 0;
min = 0;
hr = 0;
document.getElementById('hours').value = 00;
$('.node-form .form-item:nth-child(3) input').val('0');
document.getElementById('minutes').value = 00;
$('.node-form .form-item:nth-child(4) input').val('0');
document.getElementById('seconds').value = 00;
}
function putInTimelog() {
// Put hours
var hourItems = [];
var hourFields = document.getElementById("node-form").getElementsByTagName("input");
for (var i = 0; i < hourFields.length; i++) {
//omitting undefined null check for brevity
if (hourFields[i].id.lastIndexOf("edit-field-timelog-hours-0-value-", 0) === 0) {
hourItems.push(hourFields[i]);
}
}
var hourField = 'edit-field-timelog-hours-0-value-';
hourField = hourField.concat(hourItems.length);
document.getElementById(hourField).value = hr;
// Put minutes
var minuteItems = [];
var hourFields = document.getElementById("node-form").getElementsByTagName("input");
for (var i = 0; i < hourFields.length; i++) {
//omitting undefined null check for brevity
if (hourFields[i].id.lastIndexOf("edit-field-timelog-minutes-0-value-", 0) === 0) {
minuteItems.push(hourFields[i]);
}
}
var minuteField = 'edit-field-timelog-minutes-0-value-';
minuteField = minuteField.concat(minuteItems.length);
alert(minuteField);
alert((minuteField).length);
document.getElementById(minuteField).value = min;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<form>
<span class="timer-title"><strong>Activity timer</strong></span>h:
<input id="hours" readonly="readonly" size="2" type="text" /> m:
<input id="minutes" readonly="readonly" size="2" type="text" /> s:
<input id="seconds" readonly="readonly" size="2" type="text" /><span class="timer-buttons"><input onclick="doTimer()" type="button" value="Start" /> <input onclick="stopCount()" type="button" value="Stop" /> <input onclick="resetCount()" type="button" value="Reset" /> </span>
</form>
View on JSFiddle

clock.js is my repo that might help when used in conjunction with window.setInterval(). Working example included.
Add <script src="https://rack.pub/clock.min.js"></script> to your HTML then call clock.now --> 1462248501241 each time you want a time snapshot. You can add and subtract intuitively from there.
The actual js looks like:
var clock = (function() {
// object to expose as public properties and methods such as clock.now
var pub = {};
//clock.now
Object.defineProperty(pub, "now", {
get: function () {
return Date.now();
}
});
//API
return pub;
}());
var doc = document;
var el = doc.getElementById('output');
window.setInterval(function(){
/// call your function here
el.innerHTML = clock.what.time(clock.now);
}, 500);
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://rack.pub/clock.min.js"></script>
<h2 id='output'></h2>