I have a simple animation, which is done using requestAnimationFrame (for demo purposes adapted from the example on MDN). If before the animation I show a confirm dialog, the timestamp received by the animation function is wrong. The difference between the first and second timestamps is equal to the time from the moment the confirm message was shown, until the "OK" button was clicked. This behaviour (bug?) is visible in Chrome and Opera (both running Chromium). Firefox and Internet Explorer 11 run as expected. Check the fiddle or the example below.
const cache = {
start: null,
target: null
};
function animate(timestamp) {
console.log(timestamp);
if (cache.start === null) {
cache.start = timestamp;
}
var progress = timestamp - cache.start;
cache.target.style.left = Math.min(progress / 10, 100) + 'px';
if (progress < 1000) {
requestAnimationFrame(animate);
} else {
cache.target.style.left = 0;
cache.start = null;
}
}
(function() {
const target = document.getElementsByTagName("div")[0];
cache.target = target;
const cb = document.getElementsByTagName("input")[0];
const btn = document.getElementsByTagName("button")[0];
btn.addEventListener("click", function() {
if (cb.checked) {
if (confirm("Just click 'OK' to start the animation, ok?")) {
requestAnimationFrame(animate);
}
} else {
requestAnimationFrame(animate);
}
})
})();
html,
body {
padding: 0;
margin: 0;
}
div {
width: 50px;
height: 50px;
border: 1px solid black;
background-color: yellowgreen;
position: absolute;
top: 50px;
}
button {
margin-top: 20px;
}
<button type="button">Start</button>
<label>
<input type="checkbox" />use "confirm"</label>
<div>
</div>
Open the console to see the received timestamps. The animation is set to run for 2 seconds. When showing the confirm dialog, if the "OK" button gets clicked faster than 2 seconds, the animation runs for the "remaining" time. If the time needed to click the "OK" button is longer than the time animation time, the element will not be animated and there will be 2 values (timestamps) sent to the console; the difference of these 2 values is the time needed to click the "OK" button.
I assume that this is a bug in Chromium. Is there a workaround for this (still animating with requestAnimationFrame, not trough CSS)? I couldn't find anything regarding this in their tracker. Does anybody have additional info on this?
I have to say, I found this very interesting.
After spending to much time on it I may have found a workaround for you. You can see that here. https://jsfiddle.net/qtj467n0/13/
The basic gist of it is, I replaced the DOMHighResTimeStamp that requestAnimationFrame provides with performance.now() which also returns a DOMHighResTimeStamp.
const cache = {
start: null,
target: null,
time: 2000
};
function animate(timestamp) {
console.log(timestamp);
if (cache.start === null) {
cache.start = timestamp;
}
var progress = timestamp - cache.start;
cache.target.style.left = Math.min(progress / 10, cache.time / 10) + 'px';
if (progress < cache.time) {
requestAnimationFrame(animate);
} else {
cache.target.style.left = 0;
cache.start = null;
}
}
const render = () => {
requestAnimationFrame((timestamp) => {
const performanceNow = performance.now();
animate(performanceNow)
});
}
(function() {
const target = document.getElementsByTagName("div")[0];
cache.target = target;
const cb = document.getElementsByTagName("input")[0];
const btn = document.getElementsByTagName("button")[0];
btn.addEventListener("click", function() {
if (cb.checked) {
const confirmed = confirm("Just click 'OK' to start the animation, ok?");
if (confirmed) {
render();
}
} else {
requestAnimationFrame(animate);
}
})
})();
html,
body {
padding: 0;
margin: 0;
}
div {
width: 50px;
height: 50px;
border: 1px solid black;
background-color: yellowgreen;
position: absolute;
top: 50px;
}
button {
margin-top: 20px;
}
<button type="button">Start</button>
<label>
<input type="checkbox" />use "confirm"</label>
<div>
</div>
Related
I have a div which is displayed with onclick then which disappear with setTimeout:
css
#light {
position:absolute;
left:40px;
top:45px;
border-left:50px solid transparent;
border-right:50px solid transparent;
border-bottom:20px solid red;
opacity:0;
}
js (don't know if the syntax is correct but it works)
function change() {
var element = document.getElementById("light");
element.style.opacity = "1";
element.style.transitionDelay = "4s", // only the 1stime with onclick
setTimeout(() => {
element.style.opacity = "0";
}, 5000)
}
html
<button onclick="change()">light</button>
<div id="light"></div>
What I would like is that this action repeats then by itself every 2 minutes:
- after 2min, #light is displayed again for 5s (opacity="1")
- then hidden again (opacity="0")and so on, and so every 2 min.I know about the setInterval() method but it's too difficult for me to use it correctly - the script doesn't work at regular interval (every 2 min).ps: I've looked similar questions but all this is beyond my competence (ie, 0).
I'm not sure why you can't use timeouts?
Wouldn't something like this work?
( you can adjust the timers... I didn't want to wait minutes to see the light blink so I set it to few seconds)
let timer;
let started = false;
let delayTimer;
const lightOn = (clicked) => {
// do nothing if clicked for the second time
if (clicked && started) {return;}
const fn = () => {
const element = document.getElementById("light");
element.classList.add('light-on');
timer = setTimeout(lightOff, 1000);
};
if (clicked) {
delayTimer = setTimeout(fn, 3000);
} else {
fn();
}
started = true;
}
const lightOff = () => {
const element = document.getElementById("light");
element.classList.remove('light-on');
timer = setTimeout(lightOn, 2000);
}
const stop = () => {
clearTimeout(timer);
clearTimeout(delayTimer);
timer = undefined;
delayTimer = undefined;
started = false;
}
.light {
background-color: gray;
opacity: 0.1;
width: 2em;
height: 2em;
display: inline-block;
border: 1px solid black;
border-radius: 2em;
}
.light-on {
background-color: yellow;
opacity: 1;
}
<div id="light" class="light"></div>
<button onclick="lightOn(true)" style="display: block;">start</button>
<button onclick="stop()" style="display: block;">stop</button>
I have made custom carousel (for learning) on this web page. Carousel has 2 buttons (next and previous) and dots (each dot is 1 picture). It all works fine, but there is one problem. I want to make automatic loop carousel (to loop through images in interval of X seconds). Now i am using setInterval(nextImgShow, 2000);. But every time i click on either button (next, previous, dots) the interval changes.
Example: I have interval of 2s. If i click on a button when 1,5s has passed, the next image will only show for 0,5s. If i click it right away at 0,5s, the next image will show for 1,5s.
I already try to fix this with clearInterval();, but it does not change a thing. I also try to use clearInterval(); and than set interval again setInterval(nextImgShow, 2000); (on every button), but no luck.
I also try to use setTimeout(); but again nothing.
My wish is: If interval is 2s, when i click on either of buttons, i want to reset/set my interval back to 2s. So that every image is displayed for 2s, no matter when the button was clicked.
Can anyone help me solve this?
Below is JavaScript code and link to my web page, so you can see.
LINK: Link to page, so you can see demo
// navigation selection
const navigation = document.querySelector("ul.navigation");
const navigationToggleButton = document.querySelector(".navigation-toggle");
const navigationList = document.querySelectorAll(".navigation a");
// background image selector
const backgroundImgDiv = document.querySelector(".bg");
const previousImgBtn = document.querySelector(".prev");
const nextImgBtn = document.querySelector(".next");
const imgDotBtn = Array.from(document.querySelectorAll(".dot"));
const arrImg = ['url("img/0.jpg")', 'url("img/1.jpg")', 'url("img/2.jpg")', 'url("img/3.jpg")'];
const dot0 = document.querySelector(".dot-0");
const dot1 = document.querySelector(".dot-1");
const dot2 = document.querySelector(".dot-2");
const dot3 = document.querySelector(".dot-3");
let startImgIndex = 0;
let currentIndex = 0;
// navigation functions
function toggleNav() {
navigation.classList.toggle("active");
}
function navLink() {
navigation.classList.remove("active");
}
// background image functions
function nextImgShow() {
startImgIndex++;
if (startImgIndex === arrImg.length) {
startImgIndex = 0;
}
currentIndex = startImgIndex;
backgroundImgDiv.style.backgroundImage = arrImg[startImgIndex];
toggleDotActive(currentIndex);
}
function previousImgShow() {
startImgIndex--;
if (startImgIndex === -1) {
startImgIndex = (arrImg.length - 1);
}
currentIndex = startImgIndex;
backgroundImgDiv.style.backgroundImage = arrImg[startImgIndex];
toggleDotActive(currentIndex);
}
function dotBtnNavigate() {
if (this.classList.contains("dot-0")) {
dotBtnSet(0);
} else if (this.classList.contains("dot-1")) {
dotBtnSet(1);
} else if (this.classList.contains("dot-2")) {
dotBtnSet(2);
} else if (this.classList.contains("dot-3")) {
dotBtnSet(3);
}
}
function dotBtnSet (number) {
backgroundImgDiv.style.backgroundImage = arrImg[number];
startImgIndex = number;
currentIndex = number;
toggleDotActive(currentIndex);
}
function toggleDotActive(currentIndex) {
switch(currentIndex) {
case 0:
dot0.classList.add("dot-active");
dot1.classList.remove("dot-active");
dot2.classList.remove("dot-active");
dot3.classList.remove("dot-active");
break;
case 1:
dot0.classList.remove("dot-active");
dot1.classList.add("dot-active");
dot2.classList.remove("dot-active");
dot3.classList.remove("dot-active");
break;
case 2:
dot0.classList.remove("dot-active");
dot1.classList.remove("dot-active");
dot2.classList.add("dot-active");
dot3.classList.remove("dot-active");
break;
case 3:
dot0.classList.remove("dot-active");
dot1.classList.remove("dot-active");
dot2.classList.remove("dot-active");
dot3.classList.add("dot-active");
break;
default:
break;
}
}
// navigation events
navigationToggleButton.addEventListener("click", toggleNav);
navigationList.forEach(item => item.addEventListener("click", navLink));
// background image event
nextImgBtn.addEventListener("click", nextImgShow)
previousImgBtn.addEventListener("click", previousImgShow);
imgDotBtn.forEach(btn => btn.addEventListener("click", dotBtnNavigate));
// for touch devices (carousel navigate)
const gestureZone = document.querySelector('.img-wrap');
let touchstartX = 0;
let touchstartY = 0;
let touchendX = 0;
let touchendY = 0;
// for touch devices function (carousel navigate)
function handleGesture() {
if (touchendX <= touchstartX) {
nextImgShow();
}
if (touchendX >= touchstartX) {
previousImgShow();
}
}
setInterval(nextImgShow, 2000);
// navigation events
navigationToggleButton.addEventListener("click", toggleNav);
navigationList.forEach(item => item.addEventListener("click", navLink));
// background image event
nextImgBtn.addEventListener("click", nextImgShow);
previousImgBtn.addEventListener("click", previousImgShow);
imgDotBtn.forEach(btn => btn.addEventListener("click", dotBtnNavigate));
// for touch devices events (carousel navigate)
gestureZone.addEventListener('touchstart', function(event) {
touchstartX = event.changedTouches[0].screenX;
touchstartY = event.changedTouches[0].screenY;
}, false);
gestureZone.addEventListener('touchend', function(event) {
touchendX = event.changedTouches[0].screenX;
touchendY = event.changedTouches[0].screenY;
handleGesture();
}, false);
You should be passing the interval ID (returned from setInterval) to the clear interval function. For example:
let myIntervalID = setInterval(nextImgShow, 2000);
Then you can clear the interval doing clearInterval(myIntervalID) just make sure the variable myIntervalID is in scope when you clear it.
Your clearInterval wasn't actually clearing the interval so you ran into this problem. Once you correctly clear the interval (like above) and call the interval again (kinda like resetting the interval) your image will show for the full interval
You should assign the setInterval to a variable and use clearInterval when the user clicks on one of the buttons to change the image and then set the interval again.
<!DOCTYPE html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script>
var change;
var i = 1;
var numOfImages = 3;
$(document).ready(function(){
document.getElementById("img1").classList.add("active");
change = setInterval(function(){
changeImage();
}, 2000);
});
function changeImage(){
var elem = document.getElementById("img"+i);
elem.style.display = "none";
i++;
if(i>numOfImages){
i = 1;
}
var elemToBeShown = "#img"+i;
$(elemToBeShown).show();
}
</script>
<style>
.images{
width: 50%;
margin-left: 40%;
}
#img2{
display: none;
}
#img3{
display: none;
}
.button{
border-radius: 50%;
height: 25px;
width: 25px;
margin: 0px 15px 15px 15px;
background-color: green;
display: inline-block;
}
.button:hover{
cursor: pointer;
background-color: blue;
}
</style>
</head>
<body>
<div class="images">
<img id="img1" src="data:image/jpeg;base64,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" width="125" height="125"/>
<img id="img2" src="data:image/jpeg;base64,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" width="125" height="125"/>
<img id="img3" src="https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRkoieaGln2U5aMZQZibEmbva3LVpVVOw-GbcizRKfmZzog4B5lnw" width="125" height="125"/>
</div>
<div style="width: 100%; text-align: center; margin-top: 25px;">
<div class="button" id="button1"></div>
<div class="button" id="button2"></div>
<div class="button" id="button3"></div>
</div>
<script>
$('.button').click(function(e){
var buttonid = $(this).attr('id');
var imgid = parseInt(buttonid.substring(6, buttonid.length), 10);
if(i!=imgid){
clearInterval(change);
document.getElementById("img"+i).style.display = "none";
document.getElementById("img"+imgid).style.display = "block";
i = imgid;
change = setInterval(function(){
changeImage();
}, 2000);
}
});
</script>
</body>
</html>
I created an animation with CSS that changes the background-position of an element over time, to create a sort of scrolling effect with the background.
#keyframes stars-animate {
0% {
background-position: 0 -500px;
}
100% {
background-position: 2000px -500px;
}
}
This works perfectly. However, I also want to start to rewind the animation and create a reverse scrolling event. This is triggered by some irrelevant action.
function triggerReverse(element) {
element.style.animationDirection = 'reverse';
}
However, when I set the animation-direction to reverse, it does work, but not before it flips the entire background.
Am I doing it wrong, or is that the wrong way to do it, and if so, what is the right way?
Edit: I need to be able to reverse the animation while it is playing
UPDATE
The renewed sample code below provide the effect that enables a user to interrupt/pause the animation (during the first iteration) and immediately start to reverse the animation.
Here it is using time to control. Record the elapsed time from the beginning of animation, and calculate how to start the reverse animation. There are 2 iterations defined in css to make a whole loop. Without user intervention, the animation pauses/stops after the first iteration. But if there is, pause the iteration and immediately re-start it with a calculated animation-delay time. This will looks like an immediate reverse, however actually it is a new start.
There is also a trick on how to re-start the animation. Please refer to the code comment.
I searched around but found nobody has mentioned a similar scenario so far, nor a similar solution. Instead of to use time to control, I would like to see other better approaches.
My test also proves that different running environments render slightly different smoothness. Fortunately, here in SO is the best.
Try the solution to see if it can works well in your own scenario.
const span = document.querySelector('span'),
button = document.querySelector('button'),
duration = 10; // animation-during
let startTime;
span.addEventListener('animationstart', () => {
startTime = Date.now();
button.style.visibility = 'visible';
});
span.addEventListener('animationiteration', () => span.style.animationPlayState = 'paused');
span.addEventListener('animationend', () => {
button.style.visibility = 'hidden';
});
button.addEventListener('click', () => {
span.classList.remove('my_anim');
void span.offsetWidth; // safely apply changes
span.classList.add('my_anim');
const elapsed = Date.now() - startTime;
const delay = (elapsed < duration * 1000) ? (elapsed / 1000 - duration * 2) : -duration;
span.style.animationDelay = `${delay}s`;
span.style.animationPlayState = 'running';
});
span.my_anim {
animation: 10s 2 alternate my_move;
}
#keyframes my_move {
from {
margin-left: 0;
}
to {
margin-left: 50%;
}
}
button {
visibility: hidden;
}
<div>
<span class="my_anim">#</span>
</div>
<button>reverse</button>
This example does not use background-position for animation but a plain character.
const span = document.querySelector("span"),
button = document.querySelector("button");
span.addEventListener(
"animationiteration",
function() {
this.classList.add("paused");
button.style.visibility = "visible";
}
);
button.addEventListener(
"click",
function() {
this.style.visibility = "hidden";
span.classList.remove("paused");
}
);
span {
animation: 3s 2 alternate my_move;
}
span.paused {
animation-play-state: paused;
}
#keyframes my_move {
from {
margin-left: 0;
}
to {
margin-left: 50%;
}
}
button {
visibility: hidden;
}
<div>
<span>#</span>
</div>
<button>reverse</button>
NB: Use -webkit- prefix for css animation when necessary.
building off of #themefield's answer above - thanks, #themefield! - this way works the 'best', not perfect. (Sometimes the letter isn't in exactly the right spot when it reverses.)
The approach that worked was
a) reset animation to forward / reverse at the end
b) replace the animation with its opposite on toggling, setting a - start time to try to position it where it was.
Often it works pretty good, sometimes a lot off.
span = document.querySelector('span')
button = document.querySelector('button')
timerElement = document.querySelector('#timerId')
duration = 3; // animation-during
let startTime = Date.now();
toSec = (msec) => msec / 1000
elapsedTimeMsec = () => Date.now() - startTime
elapsedTimeSec = () => toSec(elapsedTimeMsec())
updateTimer = () => timerElement.innerHTML = `${elapsedTimeSec().toPrecision(2)}s`
let intervalHandle;
startTimer = () => {
intervalHandle = window.setInterval(() => {
updateTimer()
}, 500)
}
endTimer = () => {
window.clearInterval(intervalHandle)
intervalHandle = null
}
span.addEventListener('animationstart', () => {
startTime = Date.now();
startTimer()
});
span.addEventListener('animationiteration', () => span.style.animationPlayState = 'paused');
toggleAnimation = (shouldDelay) => {
span.classList.remove('my_anim');
void span.offsetWidth;
span.classList.add('my_anim');
if(span.style.animationDirection !== 'reverse')
span.style.animationDirection = 'reverse';
else
span.style.animationDirection = 'normal';
if(shouldDelay !== null && shouldDelay) {
span.style.animationDelay = `-${elapsedTimeSec()}s`;
} else {
span.style.animationDelay = `0s`;
}
span.style.animationPlayState = 'running';
}
span.addEventListener('animationend', () => {
endTimer()
updateTimer()
toggleAnimation();
});
button.addEventListener('click', () => {
endTimer()
updateTimer()
toggleAnimation(true) // todo pass in delay!
});
span.my_anim {
font-size: 54px;
animation: 3s 1 normal both my_move;
}
#keyframes my_move {
from {
margin-left: 0;
}
to {
margin-left: 50%;
}
}
button {
/*visibility: hidden;*/
}
#timerId {
font-size: 24px;
color: darkturquoise;
position: fixed;
bottom: 0;
left: 50%;
}
<div>
<span class="my_anim">#</span>
</div>
<button>reverse</button>
<span id="timerId"></span>
I have run into a little issue with a timer clock I was building. All went well but in short this is what it does:
user gets to set the time he/she wants to study or do any activity for
user presses start
the start button changes to a "stop" button
the timer counts down from the time chosen by the user
once the timer hits 0 the clock with stop and button changes back to "start" and everything is reset to 0:00
Note
Once the user taps the start button or the start button the device will vibrate if capable to notify the user.
The Issue
The problem I have is that when the clock is running and the user presses the "Stop Study" button, then the clock stops, yes thats good but when he/she presses the button again (which now should be a "start" button because its essentially paused), then the clock takes the time that was given and starts the clock over from that time the user gave and not continue until 0:00.
I have check out a few articles and I have used variables and switched between the Boolean state and checked if the clock is running or not.
isRunning = !isRunning
I have seen a few say that I should use:
clearInterval(name);
This doesn't work because I dont want to clear the state of the clock or maybe I am doing it wrong.
Code
The link to a fiddle can be found here: https://jsfiddle.net/ToreanJoel/c75vLf8b/
HTML
<br/>
<div class="timer" id="startingTimer">
<p class="title" id="state">Break</p>
<p id="time">00:00</p><span ng-style="{'height':fillHeight, 'background':fillColor }" class="fill" style="height: 0.933333%; background: rgb(153, 204, 0);"></span>
</div>
<br/>
<div class="session" id="toggleSessionStart">
<div class="timer control startingTimercontroller" id="startingTimercontroller">
<p class="title controlTitle" id="StartTimer">Start Study</p>
</div>
<!--<div class="timer control startingPauseTimercontroller" id="startingPauseTimercontroller">
<p class="title controlTitle" id="StartPauseTimer">Start Break</p>
</div>--></div>
<br/>
<header>
<div class="session">
<div class="sessionCtrl">
<p>session length</p>
<input type="number" class="time" id="valueTimerSession" value="10">
</div>
<!--<div class="breakCtrl">
<p>break length</p>
<input type="number" class="time" id="valueTimerBreak" value="5">
</div>--></div>
</header>
CSS
body {
background: #333333;
color: #fff;
}
#time {
font-size: 90px;
position: relative;
top: -40px;
}
#media (max-width: 500px) {
#time {
font-size: 90px;
position: relative;
top: -80px;
}
}
.plus {
background-color: #333333;
color: #fff;
border: none;
cursor: pointer;
font-size: 2em;
outline: none;
}
.time {
font-size: 2.5em;
padding-left: 10px;
padding-right: 10px;
width: 100%;
}
.minus {
background-color: #333333;
color: #fff;
border: none;
cursor: pointer;
font-size: 2em;
outline: none;
}
header {
display: flex;
justify-content: center;
text-align: center;
margin: 0 auto;
color: #fff;
text-transform: uppercase;
padding: 20px;
}
.session .breakCtrl, .session .sessionCtrl {
display: inline;
padding-left: 30px;
padding-right: 30px;
}
.session {
font-size: .8em;
display: flex;
}
.timer {
margin: 0 auto;
text-align: center;
width: 300px;
height: 300px;
font-size: 4em;
border: 2px solid #99CC00;
border-radius: 50%;
cursor: pointer;
position: relative;
z-index: 20;
overflow: hidden;
}
.control {
margin: 0 auto;
text-align: center;
width: 120px;
height: 120px;
font-size: 4em;
border: 2px solid #99CC00;
border-radius: 50%;
cursor: pointer;
position: relative;
z-index: 20;
overflow: hidden;
font-family: sans-serif;
}
.startingTimercontroller {
background: #37B703 !important;
border: 2px solid #fff;
}
.startingPauseTimercontroller {
background: #B70000 !important;
border: 2px solid #fff;
}
.title {
margin: 45px;
margin-bottom: -30px;
}
.controlTitle {
font-size: 28px;
position: relative;
top: 25px;
margin: 0;
}
.heading {
text-align: center;
font-size: 50px;
text-transform: uppercase;
font-family: sans-serif;
}
JS
//event Listener
var clickStart = document.getElementById("toggleSessionStart");
//pauseing the clock
var clockRunning = false;
var clicked = false;
//getting the user value ammount to study and break for
var valueTimerSession = parseInt(document.getElementById('valueTimerSession').value);
function pomodoro(studyTime) {
this.studyTime = studyTime;
this.seconds = 59;
this.timerDOM = document.getElementById("time");
this.state = document.getElementById("state");
this.toggleSessionStart = document.getElementById('toggleSessionStart');
}
pomodoro.prototype.startStudyTicker = function () {
var thisStudyTicker = this;
var seconds = this.seconds - 1;
var DOM = this.timerDOM;
var minutes = this.studyTime - 1;
var loopingSeconds = seconds;
var state = this.state;
var toggleSessionStart = this.toggleSessionStart;
if (clicked && clockRunning) {
console.log('We are runnung');
window.ticker = setInterval(function () {
//save the minutes to global variable
window.minSaved = minutes;
window.secSaved = loopingSeconds;
console.log("The time saved is " + window.minSaved + ":" + window.secSaved);
console.log(minutes + ":" + loopingSeconds);
var tick = loopingSeconds--;
if (loopingSeconds >= 0) {
tick;
DOM.innerHTML = minutes.toString() + ":" + (loopingSeconds < 10 ? '0' + loopingSeconds.toString() : loopingSeconds.toString());
} else {
if (minutes > 0) {
minutes--;
loopingSeconds = seconds;
tick;
DOM.innerHTML = minutes.toString() + ":" + (loopingSeconds < 10 ? '0' + loopingSeconds.toString() : loopingSeconds.toString());
}
if (minutes <= 0) {
//vibrate - Timer is Done
window.navigator.vibrate(300);
console.log('im finished');
clearInterval(ticker);
}
}
}, 1000);
} else {
if (!clicked && !clockRunning) {
clearInterval(ticker);
}
}
}
pomodoro.prototype.stopStudyTicker = function () {
var thisStudyTickerStop = this;
console.log('We are paused');
clearInterval(ticker);
thisStudyTickerStop.startStudyTicker();
}
//get the session title
var sessionTitle = document.getElementById('state');
//the DOM toggle
function toggleDOM(chosenTime) {
if (clicked && clockRunning) {
//started the session - the Title
sessionTitle.innerHTML = "Session";
clickStart.innerHTML =
'<div class="timer control startingPauseTimercontroller" id="startingPauseTimercontroller"><p class="title controlTitle" id="StartTimer">Stop Study</p></div>';
//vibrate
window.navigator.vibrate(300);
//prototype execution
var startStudy = new pomodoro(chosenTime);
startStudy.startStudyTicker();
} else {
sessionTitle.innerHTML = "Break";
clickStart.innerHTML =
'<div class="timer control startingTimercontroller" id="startingTimercontroller"><p class="title controlTitle" id="StartTimer">Start Study</p></div>';
//vibrate
window.navigator.vibrate([100, 100, 100]);
//prototype execution
var stopStudy = new pomodoro();
stopStudy.stopStudyTicker();
}
}
clickStart.addEventListener('click', function () {
//user clicked and the clock starts
clicked = !clicked;
clockRunning = !clockRunning;
//valueTimerBreak = parseInt(document.getElementById('valueTimerBreak').value);
valueTimerSession = parseInt(document.getElementById('valueTimerSession').value);
//the Toggle
toggleDOM(valueTimerSession);
});
I was looking at a few things on stack overflow but nothing really seemed to help as im not trying to use multiple buttons to pause or play but use one that toggles its states and the markup and the layout can be seen on jsFiddle (https://jsfiddle.net/ToreanJoel/c75vLf8b/).
I'm using Prototypal Pattern and I'm not use to it yet but I will be going over everything again just to refactor the code anyway to get use to it.
Thanks in advance
I didn't really understood your code but I made my own, basically if you click on a button and the seconds aren't stored in a variable - store them, else just continue looping. I think you'll understand my code, just replace your javascript with my.
var clickStart = document.getElementById("toggleSessionStart");
var pomodoro = function() {
this.inProgress = false;
this.studyTime = null;
this.timerInstance = null;
this.timerDOM = document.getElementById("time");
this.stateElement = document.getElementById("state");
this.toggleSessionStart = document.getElementById('toggleSessionStart');
}
pomodoro.prototype = {
start: function() {
var parent = this;
if(this.studyTime === null) this.studyTime = parseInt(document.getElementById('valueTimerSession').value, 10) * 60;
this.timerInstance = setInterval(function() {
parent.studyTime--;
if(parent.studyTime < 1) parent.destroy();
else parent.updateTime();
}, 1000);
return this;
},
pause: function() {
clearInterval(this.timerInstance);
this.timerInstance = null;
return this;
},
destroy: function() {
this.pause();
this.studyTime = null;
this.toogleState(false);
this.timerDOM.innerHTML = '00:00';
return this;
},
updateTime: function() {
var totalSec = this.studyTime,
minutes = Math.floor(totalSec / 60),
seconds = totalSec % 60;
this.timerDOM.innerHTML = (minutes < 10 ? "0" + minutes : minutes) + ":" + (seconds < 10 ? "0" + seconds : seconds);
return this;
},
toogleState: function(state) {
this.inProgress = (typeof state !== 'undefined') ? state : !this.inProgress;
if(this.inProgress) {
this.stateElement.innerHTML = "Session";
clickStart.innerHTML = '<div class="timer control startingPauseTimercontroller" id="startingPauseTimercontroller"><p class="title controlTitle" id="StartTimer">Stop Study</p></div>';
this.start();
}
else {
this.stateElement.innerHTML = "Break";
clickStart.innerHTML = '<div class="timer control startingTimercontroller" id="startingTimercontroller"><p class="title controlTitle" id="StartTimer">Start Study</p></div>';
this.pause();
}
window.navigator.vibrate(300);
return this;
}
};
var pomodoroInstance = new pomodoro();
clickStart.addEventListener('click', function () {
pomodoroInstance.toogleState();
});
BTW. there is one problem, you can't stop the timer manually so if user wants to set different time he will have to reload the page. You can add a little button which will trigger destroy() method.
I'd rather implement the logic for the clock in a separate class, after all a clock doesn't need anything but a time, our api will consist on methods to start/stop/pause the timer
The gui then creates a clock instance, whenever you click the start/stop button we just need to call the magic clock methods that control the timer, note that the clock doesn't have a method to render itself, it'd be better to have another class like ClockGUI that has an inner instance of Clock, this new class would just call methods of the Clock instance to update the timer and also update the gui
function Clock (time) {
this.timeLeft = time
this.paused = false
}
Clock.prototype.start = function () {
this.raf = requestAnimationFrame(
this._loop.bind(this)
)
}
Clock.prototype.stop = function () {
cancelRequestAnimationFrame(this.raf)
}
Clock.prototype.togglePause = function () {
this.paused = !this.paused
}
Clock.prototype._update = function (t) {
if (!this.paused) {
this.timeLeft -= t
if (this.timeLeft <= 0) {
this.stop()
}
}
}
Clock.prototype._loop = function () {
this.raf = requestAnimationFrame(this._loop.bind(this))
var now = Date.now()
var delta = now - (this.prev || now)
this._update(delta)
this.prev = now
}
// game
var timeLeft = document.querySelector('#time-left')
var input = document.querySelector('input')
var button = document.querySelector('button')
var started = false
var clock
button.addEventListener('click', function () {
button.innerText = button.innerText === 'start' ? 'pause' : 'start'
if (!started) {
started = true
clock = new Clock(input.value * 1000 * 60)
clock.start()
input.disabled = true
return
}
// toggle the state of the clock
clock.togglePause()
})
function render () {
requestAnimationFrame(render)
// render only if a clock was created
if (clock) {
var time = Math.floor(clock.timeLeft / 1000)
var minutes = Math.floor(time / 60)
var seconds = time % 60
var ms = clock.timeLeft % 1000
timeLeft.innerHTML = minutes + ':' + seconds + ':' + ms
}
}
requestAnimationFrame(render)
<div>
Time left: <span id="time-left"></span>
</div>
<button> start </button>
<input type="number" value="10">
As you've seen the clock is not controlled by setInterval but by requestAnimationFrame, the problem of having a fixed 1000 ms interval is the pause behavior you want:
pause: just call clearInterval
start: compute how much time is left that isn't part of a second e.g. timeLeft % 1000, set a timeout on that much time left and then call set interval again
You could use setInterval with a small frequency like 10ms, however it's not guaranteed that the function will be called with exactly 10ms but as close as 10ms therefore you still need to compute the time elapsed between two calls of the setInterval function, in the example above this is done on Clock.prototype._loop
Hi I'm working on a reaction test that checks how fast it takes for the user before they react, and I can't really find what I'm looking for. I was just wondering how to make a simple stopwatch in seconds and milliseconds so I can call the function later in HTML onclick.
Here is my code so far:
HTML
<input type="button" class="first" value="Call" onclick="call function" />
and that's pretty much it... I know HTML, CSS, JavaScript and a little bit jQuery.
Thanks in advance !
As a basic starting point you want to use setInterval to increment the stopwatch, with an additional function to toggle/reset it.
You can then either bind the click handler directly to the button (per below), or - I would tend to recommend you bind it in the Javascript itself (e.g. with .onclick=function(){....})
var s = 0,
ms = 0,
sEl = document.getElementById('s'),
msEl = document.getElementById('ms'),
play = false;
stopwatch = setInterval(function() {
if (!play) return;
if (ms === 99) {
s += 1;
ms = 0;
} else {
ms += 1;
}
update();
}, 1);
function update() {
sEl.innerText = s;
msEl.innerText = ms;
}
function toggle() {
if (!play) {
s = 0, ms = 0;
update();
}
play = !play;
}
body {
font-family: arial;
}
#s {
font-size: 50px;
}
#ms {
font-size: 30px;
display:inline-block;
width:35px;
}
button {
border: 1px solid grey;
background: lightgrey;
padding: 10px 40px;
}
<span id="s">0</span>s <span id="ms">00</span>ms
<br />
<button onclick="toggle();">Toggle</button>