How to make this countdown repeat after the time runs out? - javascript

I'm very new to Javascript and I found myself stuck with this issue. I want to make this countdown repeat after the time runs out, however I'm not really sure how to do it, and my attempts to make it work failed. Would appreciate help how to do it, Thanks.
function startTimer(duration, display) {
var timer = duration, minutes, seconds;
setInterval(function () {
minutes = parseInt(timer / 60, 10);
seconds = parseInt(timer % 60, 10);
minutes = minutes < 10 ? "0" + minutes : minutes;
seconds = seconds < 10 ? "0" + seconds : seconds;
display.textContent = minutes + ":" + seconds;
if (--timer < 0) {
// here's the problem. not sure how to make it repeat
}
}, 1000);
}
window.onload = function () {
var fiveMinutes = 60 * 5,
display = document.querySelector('#time');
startTimer(fiveMinutes, display);
};
Tried using clearInterval() and setTimeout() but instead of it working the countdown either went past 00:00 (00:0-1 and so on) or just didn't work at all.

You can reset timer:
function startTimer(duration, display) {
var timer = duration, minutes, seconds;
setInterval(function () {
minutes = parseInt(timer / 60, 10);
seconds = parseInt(timer % 60, 10);
minutes = minutes < 10 ? "0" + minutes : minutes;
seconds = seconds < 10 ? "0" + seconds : seconds;
display.textContent = minutes + ":" + seconds;
if (--timer < 0) {
timer = duration;
}
}, 1000);
}

What you're describing is a forever countdown.
Note that eventhough you specify 1000 in the setInterval(). The timer isn't precise, so the callback may fire less than or greater than 1000ms. It is much safer to capture the startTime and then calculate the currentTime when the callback fires and measure the elapsedTime. This will give a true indication of elapsed time regardless of whether the timer is running slow or fast.
Because of the reset requirement. I actually infer that the timer is an infinite loop. We run it forever. There is no description as to when the timer is aborted, so, we just continue measuring currentTime and note elapse.
I use elapsedTime = (currentTime - startTime) / 1000 to calculate the elapsed time in seconds. Then, I elapsed % duration to make the counter stop at the duration and reset. Finally, I flip the math countdown = duration - 1 - (elapsedTime % duration) so instead of counting up, it counts down.
We then break down countdown into the minutes and seconds components.
Below is a fully working example that uses jQuery.
function startTimer(duration, display) {
let startTime = Date.now();
setInterval(function() {
let currentTime = Date.now();
let elapsedTime = Math.floor((currentTime - startTime) / 1000);
let countdown = duration - 1 - (elapsedTime % duration);
let minutes = Math.floor(countdown / 60).toString().padStart(2, "0");
let seconds = (countdown % 60).toString().padStart(2, "0");
display.text(minutes + ":" + seconds);
}, 1000 );
}
let fiveMinutes = 60 * 5;
let display = $("#time");
startTimer(fiveMinutes, display);
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<label id="time">mm:ss</label>

Related

How do you escape out of an alert box and resume flow of action? - Javascript

So i am writing a simple javascript timer, and at 30 seconds it prompts the user with an alert box if they would like to reset the count down or let it continue.
I am able to reset the timer however I get stuck when the user clicks cancel on the alert box.
I tried letting the timer just resume at its current time but that doesn't help as the alert box just keeps reappearing
I am still very new to javascript so I would like to stay using vanilla js till I get a deeper understanding of the fundamentals!
Any guidance would be greatly appreciated!
Heres my code:
function startTimer(duration, display) {
var timer = duration, minutes, seconds;
setInterval(function () {
minutes = parseInt(timer / 60, 10);
seconds = parseInt(timer % 60, 10);
minutes = minutes < 10 ? "0" + minutes : minutes;
seconds = seconds < 10 ? "0" + seconds : seconds;
display.textContent = minutes + ":" + seconds;
if(timer<30){
var message = confirm("Would you like to extend timer?");
if (message == true) {
timer = 60 * 1;
}
else{
timer = timer;
}
}
if (--timer < 0) {
timer = duration;
}
}, 1000);
}
function resetTimer() {
timer = 60 * 1;
}
window.onload = function () {
var fiveMinutes = 60 * 1,
display = document.querySelector('#time');
startTimer(fiveMinutes, display);
};
just put if(timer==30) instead of if(timer<30) so that exactly at count of 30 units of time, you get asked once for confirmation at that instance (However be aware that until the confirmation is done, prompts will keep popping up every second). if you extend it, it will again wait till your timer goes down to 30 unit, else it will simply go down to 0 and break out.
function startTimer(duration, display) {
var timer = duration,
minutes,
seconds;
function timerFunc() {
timer -= 1;
minutes = parseInt(timer / 60, 10);
seconds = parseInt(timer % 60, 10);
minutes = minutes < 10 ? "0" + minutes : minutes;
seconds = seconds < 10 ? "0" + seconds : seconds;
display.textContent = minutes + ":" + seconds;
if (timer == 30) {
var message = confirm("Would you like to extend timer?");
if (message == true) {
timer = 60;
} else return alert("Your timer has been stopped.")
}
setTimeout(timerFunc, 1000);
}
timerFunc();
}

How to prevent countdown timer from resetting when webpage is refreshed?

I am designing a website and I integrated a 5 minute countdown timer that starts when the web-page is loaded, using JavaScript. However, since I am more of a designer than a developer, I don't know how to edit the JavaScript code to make it so that the timer does not restart when the webpage is reloaded. I know I have to store the users cookies, and I've searched online, but the javascript code didnt work when I inserted the code. Would anyone here be able to help me out? Thank you!
Here is the javascript code for the 5 minute timer:
function startTimer(duration, display) {
var timer = duration, minutes, seconds;
setInterval(function () {
minutes = parseInt(timer / 60, 10)
seconds = parseInt(timer % 60, 10);
minutes = minutes < 10 ? "0" + minutes : minutes;
seconds = seconds < 10 ? "0" + seconds : seconds;
display.textContent = minutes + " " + " " + seconds;
if (--timer < 0) {
timer = duration;
}
}, 1000);
}
window.onload = function () {
var fiveMinutes = 60 * 5,
display = document.querySelector('#time');
startTimer(fiveMinutes, display);
};
Check this approach where the time is stored in local storage of the browser and hence on refresh will not reset:
:HTML CODE:
<div id="time">
</div>
:JS CODE:
function startTimer(duration, display) {
var timer = duration, minutes, seconds;
setInterval(function () {
minutes = parseInt(timer / 60, 10)
seconds = parseInt(timer % 60, 10);
minutes = minutes < 10 ? "0" + minutes : minutes;
seconds = seconds < 10 ? "0" + seconds : seconds;
display.textContent = minutes + " " + " " + seconds;
if (--timer < 0) {
timer = duration;
}
console.log(parseInt(seconds))
window.localStorage.setItem("seconds",seconds)
window.localStorage.setItem("minutes",minutes)
}, 1000);
}
window.onload = function () {
sec = parseInt(window.localStorage.getItem("seconds"))
min = parseInt(window.localStorage.getItem("minutes"))
if(parseInt(min*sec)){
var fiveMinutes = (parseInt(min*60)+sec);
}else{
var fiveMinutes = 60 * 5;
}
// var fiveMinutes = 60 * 5;
display = document.querySelector('#time');
startTimer(fiveMinutes, display);
};
Here is the working model of the same in the codepen https://codepen.io/anon/pen/GymRNV?editors=1011
P.S: couldn't use it here as it is a sandbox and cant access localstorage.
You should use web "Session storage" api for this case. it will much help you.
https://developer.mozilla.org/en-US/docs/Web/API/Window/sessionStorage
sorry var distance = localStorage.getItem("mytime") - now;var x =localStorage.getItem("mytime"); I spent about 6 weeks figuring this out,it works,you need localstorage but only on countdown,now still has to function so counter counts,countdown is the anchor,look at w3school there countdown is set thats why it works,and thats were you use localstorage
use w3 school countdown timer,countdown date use localstorage.mytime=setDate(d.getDate + 7),also at end if distance < 0;localStorageremoveItem, thats it ,run code

countdown timer with number reduction after set point?

I've got a working countdown timer which starts at 30 minutes.
With only 3 minutes left (so after 27 minutes) I'd like the number 250 to decrease at random intervals from 3 minutes left down to the end of the countdown.
Any ideas?
https://codepen.io/anon/pen/bWoGrb
// Stopwatch
function startTimer(duration, display) {
var timer = duration, minutes, seconds;
setInterval(function () {
minutes = parseInt(timer / 60, 10)
seconds = parseInt(timer % 60, 10);
minutes = minutes < 10 ? "0" + minutes : minutes;
seconds = seconds < 10 ? "0" + seconds : seconds;
display.textContent = minutes + ":" + seconds;
if (--timer < 0) {
timer = duration;
}
}, 1000);
}
window.onload = function () {
var thirtyMinutes = 60 * 30,
display = document.querySelector('#stopwatch');
startTimer(thirtyMinutes, display);
};
<div id='stopwatch'></div>
Maybe use something like this (I hope I clearly understood the question):
Just using a if/else within the condition something to say: Go normal when more than 60*3, and when under 60*3 seconds rest, there is chance to do nothing
// Stopwatch
function startTimer(duration, display) {
var timer = duration, minutes, seconds;
setInterval(function () {
if(timer > 60*3 || Math.random() < 0.25) {
minutes = parseInt(timer / 60, 10)
seconds = parseInt(timer % 60, 10);
minutes = minutes < 10 ? "0" + minutes : minutes;
seconds = seconds < 10 ? "0" + seconds : seconds;
display.textContent = minutes + ":" + seconds;
if (--timer < 0) {
timer = duration;
}
} else {
/* do not reduce the timer to wait 1 interval more */
/* or maybe do like `timer -= Math.random()` if you want to reduce it faster */
}
}, 1000);
}
window.onload = function () {
var thirtyMinutes = 60 * /*30*/ 4, // just set to 4 to see faster
display = document.querySelector('#stopwatch');
startTimer(thirtyMinutes, display);
};
<div id='stopwatch'></div>

I need some explanation for some of this code

This a count down timer. I don't understand how var timer works. What is its set value after each interval? How does the timer produce the number of minutes and seconds? Could some one break down step-by-step how this bit of code operates?
minutes = parseInt(timer / 60, 10);
seconds = parseInt(timer % 60, 10);
minutes = minutes < 10 ? "0" + minutes : minutes;
seconds = seconds < 10 ? "0" + seconds : seconds;
Here is the complete code:
function startTimer(duration, display) {
var timer = duration, minutes, seconds;
setInterval(function () {
minutes = parseInt(timer / 60, 10);
seconds = parseInt(timer % 60, 10);
minutes = minutes < 10 ? "0" + minutes : minutes;
seconds = seconds < 10 ? "0" + seconds : seconds;
display.textContent = minutes + ":" + seconds;
if (--timer < 0) {
timer = duration;
}
}, 1000);
}
window.onload = function () {
var fiveMinutes = 60 * 5,
display = document.querySelector('#time');
startTimer(fiveMinutes, display);
minutes = parseInt(timer / 60, 10);
Minutes are number of current total seconds divided by 60 (seconds in a minute).
E.g.: 65 / 60 = 1 minute. We just keep the integer part.
seconds = parseInt(timer % 60, 10);
Seconds are calculated as the module 60 of the current total seconds counter.
E.g.: 65 % 60 = 5 (1 minute, 5 seconds)
[Notice that in the second line the parseInt is unnecessary.]
var timer = duration, seconds, minutes;
this can also be written as:
var timer = duration;
var seconds;
var minutes;
You can declare and instialise multiple variables at a time in javascript.
var a,
b,
c;
is same as
var a;
var b;
var c;
also you can intialize variable too so
var timer = duration, seconds, minutes;
is same as writing
var timer = duration;
var seconds;
var minutes;
(as #Lorenzo already mentioned)
var timer = duration, seconds, minutes declares 3 variables with only the first getting initialized. It is the same as writing:
var timer = duration;
var seconds;
var minutes;

Reset 'setIntervall' counter / remove existing instances

A timer will count down from 10 minutes on loading the page. If I do a mousedown after some time, the countdown should start again.
But then the timer will jump between both values. It seems, that both are counting. How can I remove exiting intervals?
Template.content.onRendered(function() {
var display = document.querySelector('#timer');
startTimer( 600, display);
});
Template.content.events({
'mousedown': function() {
var display = document.querySelector('#timer');
startTimer( 600, display);
// this will start a new counter
// but I want the old one to be replaced
}
});
startTimer = function(duration, display) {
var start = Date.now(),
diff,
minutes,
seconds;
function timer() {
diff = duration - (((Date.now() - start) / 1000) | 0);
minutes = (diff / 60) | 0;
seconds = (diff % 60) | 0;
minutes = minutes < 10 ? "0" + minutes : minutes;
seconds = seconds < 10 ? "0" + seconds : seconds;
display.textContent = minutes + ":" + seconds;
}
timer();
setInterval(timer, 1000);
};
Add a new variable in your js
var timer = 0;
Update your code in startTimer function from
setInterval(timer, 1000);
to
timer = setInterval(timer, 1000);
And then in your mousedown event handler function, add following line
clearInterval(timer);

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