I have an object rotating on z axis. onMouseDown the rotation stops and onMouseUp the rotation resumes after 2 seconds.
Is there a way for the rotation to resume slowly (like ease in for css)?
The code for the rotation start and stop.
if ( etaj1 !== undefined ) {
etaj1.rotation.z += delta * 0;
if(!isMouseDown){
etaj1.rotation.z += delta * 0.05 ;
}
}
Also there is a resetTimer condition if a new click is made before the 2 seconds have passed.
var timerHandle = setTimeout (wait , 2000);
function resetTimer () {
window.clearTimeout (timerHandle);
timerHandle = setTimeout (wait , 2000);
}
function onMouseDown(){
console.log("Mouse DOWN");
isMouseDown = true;
}
function onMouseUp(){
window.clearTimeout (timerHandle);
timerHandle = setTimeout (wait , 2000);
}
function wait (){
resetTimer;
console.log("Mouse UP");
isMouseDown = false;
}
the idea is to make a transition for isMouseDown = false; and another transition for isMouseDown = true;
Basically what i want to do is stop the rotation from the link below with a quart.out tween, wait 2 seconds and if no click resume rotation with a quart.in tween.
https://threejs.org/examples/#webgl_loader_collada
Thanks.
I'm not a three.js guy, however what you are asking is applicable in other areas as well. So I will put here a general solution. First the proof of concept:
https://jsfiddle.net/ibowankenobi/u4xwnLam/4/
I'll start declaring the globals I need, wrap them up as you want:
var rotation = 0;
var bar = document.getElementById("bar");
var container = document.getElementById("container");
I need to demonstrate this without three.js so I need to have a container and something to rotate so you do not need bar and container in your case. Rotation in your case is your etaj1.rotation.z
We first need a function that will map 0-1 to 0-1 again, but not linearly. These are called interpolations, there are many ones, cosine, this, that, most widely used one is a stitched and transformed x^3 and gives a "slow in slow out" affect:
function slowInSlowOut(t){
if(2*t<<0){
return 4*(t-1)*(t-1)*(t-1)+1;
} else {
return 4*t*t*t;
}
}
We have to do something with this function so I will write another animate
function changeSpeed(obj,newSpeed){
var oldSpeed = obj.__oldSpeed || 0;
var startTime;
newSpeed = newSpeed || 0;
obj.__currentFrame && window.cancelAnimationFrame(obj.__currentFrame);//cancel a previous changeSpeed if fired twice
obj.__currentFrame = window.requestAnimationFrame(anim);
function anim(t){
startTime = startTime || t;
var elapsed = t - startTime,
parametric = slowInSlowOut(elapsed/2000);
if(parametric>=1){
obj.__oldSpeed = newSpeed;
} else {
obj.__oldSpeed = newSpeed + (oldSpeed-newSpeed) * (1-parametric);
obj.__currentFrame = window.requestAnimationFrame(anim);
}
}
}
You provide this function an object, and it will attach it a proprietary __oldSpeed property, the newSpeed parameter is measured in means of degrees/17ms (because I am using requestAnimationFrame and that will fire each ~17ms). So in your case the obj is your etaj1.
Within this function you can already update your etaj1.rotation.z if you want. But I will write a third function to fire continuously and listen to __oldSpeed property and take action based on that:
function animate(obj){
rotation += (obj.__oldSpeed || 0);
rotation = rotation % 360;
obj.style.transform = "rotate("+rotation+"deg)";
window.requestAnimationFrame(function(){animate(obj)});
}
Again here, obj is your etaj1 and rotation is etaj1.rotation.z. I am using DOM here, so I need to use the styles. You can adapt it to your case.
Animate won't fire, so we need to fire him:
window.requestAnimationFrame(function(){animate(bar)});
I'll add the eventListeners as you described:
container.addEventListener("mousedown",function(){changeSpeed(bar,0)},false);
container.addEventListener("mouseup",function(){changeSpeed(bar,12)},false);
Now we give it a starting speed:
changeSpeed(bar,12);
There you go. In case you wondered how to do it yourself, this might get you started. I guess people using other technology stacks can also adapt this to their case.
PS:
Someone mentioned a delay, in that case modify the changeSpeed a bit:
function changeSpeed(obj,newSpeed,delay){
delay = delay || 0;
var oldSpeed = obj.__oldSpeed || 0;
var startTime;
newSpeed = newSpeed || 0;
obj.__currentFrame && window.cancelAnimationFrame(obj.__currentFrame);
obj.__currentFrame = window.requestAnimationFrame(anim);
function anim(t){
startTime = startTime || t;
var elapsed = t - startTime;
if(elapsed < delay) {
return obj.__currentFrame = window.requestAnimationFrame(anim);
}
var parametric = slowInSlowOut((elapsed-delay)/2000);
if(parametric>=1){
obj.__oldSpeed = newSpeed;
} else {
obj.__oldSpeed = newSpeed + (oldSpeed-newSpeed) * (1-parametric);
obj.__currentFrame = window.requestAnimationFrame(anim);
}
}
}
Here is a fiddle that has a 2 second delay:
https://jsfiddle.net/ibowankenobi/u4xwnLam/10/
I need to create a simple but accurate timer.
This is my code:
var seconds = 0;
setInterval(function() {
timer.innerHTML = seconds++;
}, 1000);
After exactly 3600 seconds, it prints about 3500 seconds.
Why is it not accurate?
How can I create an accurate timer?
Why is it not accurate?
Because you are using setTimeout() or setInterval(). They cannot be trusted, there are no accuracy guarantees for them. They are allowed to lag arbitrarily, and they do not keep a constant pace but tend to drift (as you have observed).
How can I create an accurate timer?
Use the Date object instead to get the (millisecond-)accurate, current time. Then base your logic on the current time value, instead of counting how often your callback has been executed.
For a simple timer or clock, keep track of the time difference explicitly:
var start = Date.now();
setInterval(function() {
var delta = Date.now() - start; // milliseconds elapsed since start
…
output(Math.floor(delta / 1000)); // in seconds
// alternatively just show wall clock time:
output(new Date().toUTCString());
}, 1000); // update about every second
Now, that has the problem of possibly jumping values. When the interval lags a bit and executes your callback after 990, 1993, 2996, 3999, 5002 milliseconds, you will see the second count 0, 1, 2, 3, 5 (!). So it would be advisable to update more often, like about every 100ms, to avoid such jumps.
However, sometimes you really need a steady interval executing your callbacks without drifting. This requires a bit more advanced strategy (and code), though it pays out well (and registers less timeouts). Those are known as self-adjusting timers. Here the exact delay for each of the repeated timeouts is adapted to the actually elapsed time, compared to the expected intervals:
var interval = 1000; // ms
var expected = Date.now() + interval;
setTimeout(step, interval);
function step() {
var dt = Date.now() - expected; // the drift (positive for overshooting)
if (dt > interval) {
// something really bad happened. Maybe the browser (tab) was inactive?
// possibly special handling to avoid futile "catch up" run
}
… // do what is to be done
expected += interval;
setTimeout(step, Math.max(0, interval - dt)); // take into account drift
}
I'ma just build on Bergi's answer (specifically the second part) a little bit because I really liked the way it was done, but I want the option to stop the timer once it starts (like clearInterval() almost). Sooo... I've wrapped it up into a constructor function so we can do 'objecty' things with it.
1. Constructor
Alright, so you copy/paste that...
/**
* Self-adjusting interval to account for drifting
*
* #param {function} workFunc Callback containing the work to be done
* for each interval
* #param {int} interval Interval speed (in milliseconds)
* #param {function} errorFunc (Optional) Callback to run if the drift
* exceeds interval
*/
function AdjustingInterval(workFunc, interval, errorFunc) {
var that = this;
var expected, timeout;
this.interval = interval;
this.start = function() {
expected = Date.now() + this.interval;
timeout = setTimeout(step, this.interval);
}
this.stop = function() {
clearTimeout(timeout);
}
function step() {
var drift = Date.now() - expected;
if (drift > that.interval) {
// You could have some default stuff here too...
if (errorFunc) errorFunc();
}
workFunc();
expected += that.interval;
timeout = setTimeout(step, Math.max(0, that.interval-drift));
}
}
2. Instantiate
Tell it what to do and all that...
// For testing purposes, we'll just increment
// this and send it out to the console.
var justSomeNumber = 0;
// Define the work to be done
var doWork = function() {
console.log(++justSomeNumber);
};
// Define what to do if something goes wrong
var doError = function() {
console.warn('The drift exceeded the interval.');
};
// (The third argument is optional)
var ticker = new AdjustingInterval(doWork, 1000, doError);
3. Then do... stuff
// You can start or stop your timer at will
ticker.start();
ticker.stop();
// You can also change the interval while it's in progress
ticker.interval = 99;
I mean, it works for me anyway. If there's a better way, lemme know.
Bergi's answer pinpoints exactly why the timer from the question is not accurate. Here's my take on a simple JS timer with start, stop, reset and getTime methods:
class Timer {
constructor () {
this.isRunning = false;
this.startTime = 0;
this.overallTime = 0;
}
_getTimeElapsedSinceLastStart () {
if (!this.startTime) {
return 0;
}
return Date.now() - this.startTime;
}
start () {
if (this.isRunning) {
return console.error('Timer is already running');
}
this.isRunning = true;
this.startTime = Date.now();
}
stop () {
if (!this.isRunning) {
return console.error('Timer is already stopped');
}
this.isRunning = false;
this.overallTime = this.overallTime + this._getTimeElapsedSinceLastStart();
}
reset () {
this.overallTime = 0;
if (this.isRunning) {
this.startTime = Date.now();
return;
}
this.startTime = 0;
}
getTime () {
if (!this.startTime) {
return 0;
}
if (this.isRunning) {
return this.overallTime + this._getTimeElapsedSinceLastStart();
}
return this.overallTime;
}
}
const timer = new Timer();
timer.start();
setInterval(() => {
const timeInSeconds = Math.round(timer.getTime() / 1000);
document.getElementById('time').innerText = timeInSeconds;
}, 100)
<p>Elapsed time: <span id="time">0</span>s</p>
The snippet also includes a solution for your problem. So instead of incrementing seconds variable every 1000ms interval, we just start the timer and then every 100ms* we just read elapsed time from the timer and update the view accordingly.
* - makes it more accurate than 1000ms
To make your timer more accurate, you would have to round
Most of the timers in the answers here will linger behind the expected time because they set the "expected" value to the ideal and only account for the delay that the browser introduced before that point. This is fine if you just need accurate intervals, but if you are timing relative to other events then you will (nearly) always have this delay.
To correct it, you can keep track of the drift history and use it to predict future drift. By adding a secondary adjustment with this preemptive correction, the variance in the drift centers around the target time. For example, if you're always getting a drift of 20 to 40ms, this adjustment would shift it to -10 to +10ms around the target time.
Building on Bergi's answer, I've used a rolling median for my prediction algorithm. Taking just 10 samples with this method makes a reasonable difference.
var interval = 200; // ms
var expected = Date.now() + interval;
var drift_history = [];
var drift_history_samples = 10;
var drift_correction = 0;
function calc_drift(arr){
// Calculate drift correction.
/*
In this example I've used a simple median.
You can use other methods, but it's important not to use an average.
If the user switches tabs and back, an average would put far too much
weight on the outlier.
*/
var values = arr.concat(); // copy array so it isn't mutated
values.sort(function(a,b){
return a-b;
});
if(values.length ===0) return 0;
var half = Math.floor(values.length / 2);
if (values.length % 2) return values[half];
var median = (values[half - 1] + values[half]) / 2.0;
return median;
}
setTimeout(step, interval);
function step() {
var dt = Date.now() - expected; // the drift (positive for overshooting)
if (dt > interval) {
// something really bad happened. Maybe the browser (tab) was inactive?
// possibly special handling to avoid futile "catch up" run
}
// do what is to be done
// don't update the history for exceptionally large values
if (dt <= interval) {
// sample drift amount to history after removing current correction
// (add to remove because the correction is applied by subtraction)
drift_history.push(dt + drift_correction);
// predict new drift correction
drift_correction = calc_drift(drift_history);
// cap and refresh samples
if (drift_history.length >= drift_history_samples) {
drift_history.shift();
}
}
expected += interval;
// take into account drift with prediction
setTimeout(step, Math.max(0, interval - dt - drift_correction));
}
I agree with Bergi on using Date, but his solution was a bit of overkill for my use. I simply wanted my animated clock (digital and analog SVGs) to update on the second and not overrun or under run creating obvious jumps in the clock updates. Here is the snippet of code I put in my clock update functions:
var milliseconds = now.getMilliseconds();
var newTimeout = 1000 - milliseconds;
this.timeoutVariable = setTimeout((function(thisObj) { return function() { thisObj.update(); } })(this), newTimeout);
It simply calculates the delta time to the next even second, and sets the timeout to that delta. This syncs all of my clock objects to the second. Hope this is helpful.
Here's a solution that pauses when the window is hidden, and can be cancelled with an abort controller.
function animationInterval(ms, signal, callback) {
const start = document.timeline.currentTime;
function frame(time) {
if (signal.aborted) return;
callback(time);
scheduleFrame(time);
}
function scheduleFrame(time) {
const elapsed = time - start;
const roundedElapsed = Math.round(elapsed / ms) * ms;
const targetNext = start + roundedElapsed + ms;
const delay = targetNext - performance.now();
setTimeout(() => requestAnimationFrame(frame), delay);
}
scheduleFrame(start);
}
Usage:
const controller = new AbortController();
// Create an animation callback every second:
animationInterval(1000, controller.signal, time => {
console.log('tick!', time);
});
// And stop it sometime later:
controller.abort();
Modern, Fully Programmable Timer
This timer takes a frequency in Hertz, and a callback that can take up to four arguments, the current frame index, the current time, the time that the current frame would have ideally occurred at, and a reference to the timer instance (so the caller and callback can both access its methods).
Note: All times are based on performance.now, and are relative to the moment that the page loaded.
Timer instances have three API methods:
stop: Takes no args. Kills the timer immediately (and permanently).
Returns the frame index for the next frame (the cancelled frame).
adapt: Takes a frequency in Hertz and adapts the timer to it, beginning
from the next frame. Returns the implied interval in milliseconds.
redefine: Takes a new callback function. Swaps it with the current
callback. Effects the next frame. Returns undefined.
Note: The tick method passes this around explicitly (as self) to work around the problem of this referencing window when the tick method is invoked via setTimeout.
class ProgrammableTimer {
constructor(hertz, callback) {
this.target = performance.now(); // target time for the next frame
this.interval = 1 / hertz * 1000; // the milliseconds between ticks
this.callback = callback;
this.stopped = false;
this.frame = 0;
this.tick(this);
}
tick(self) {
if (self.stopped) return;
const currentTime = performance.now();
const currentTarget = self.target;
const currentInterval = (self.target += self.interval) - currentTime;
setTimeout(self.tick, currentInterval, self);
self.callback(self.frame++, currentTime, currentTarget, self);
}
stop() { this.stopped = true; return this.frame }
adapt(hertz) { return this.interval = 1 / hertz * 1000 }
redefine(replacement) { this.callback = replacement }
}
Doesn't get much more accurate than this.
var seconds = new Date().getTime(), last = seconds,
intrvl = setInterval(function() {
var now = new Date().getTime();
if(now - last > 5){
if(confirm("Delay registered, terminate?")){
clearInterval(intrvl);
return;
}
}
last = now;
timer.innerHTML = now - seconds;
}, 333);
As to why it is not accurate, I would guess that the machine is busy doing other things, slowing down a little on each iteration adds up, as you see.
This is an old question but figured I'd share some code I use sometimes:
function Timer(func, delay, repeat, runAtStart)
{
this.func = func;
this.delay = delay;
this.repeat = repeat || 0;
this.runAtStart = runAtStart;
this.count = 0;
this.startTime = performance.now();
if (this.runAtStart)
this.tick();
else
{
var _this = this;
this.timeout = window.setTimeout( function(){ _this.tick(); }, this.delay);
}
}
Timer.prototype.tick = function()
{
this.func();
this.count++;
if (this.repeat === -1 || (this.repeat > 0 && this.count < this.repeat) )
{
var adjustedDelay = Math.max( 1, this.startTime + ( (this.count+(this.runAtStart ? 2 : 1)) * this.delay ) - performance.now() );
var _this = this;
this.timeout = window.setTimeout( function(){ _this.tick(); }, adjustedDelay);
}
}
Timer.prototype.stop = function()
{
window.clearTimeout(this.timeout);
}
Example:
time = 0;
this.gameTimer = new Timer( function() { time++; }, 1000, -1);
Self-corrects the setTimeout, can run it X number of times (-1 for infinite), can start running instantaneously, and has a counter if you ever need to see how many times the func() has been run. Comes in handy.
Edit: Note, this doesn't do any input checking (like if delay and repeat are the correct type. And you'd probably want to add some kind of get/set function if you wanted to get the count or change the repeat value.
One of my simplest implementations is down below. It can even survive page reloads. :-
Code pen: https://codepen.io/shivabhusal/pen/abvmgaV
$(function() {
var TTimer = {
startedTime: new Date(),
restoredFromSession: false,
started: false,
minutes: 0,
seconds: 0,
tick: function tick() {
// Since setInterval is not reliable in inactive windows/tabs we are using date diff.
var diffInSeconds = Math.floor((new Date() - this.startedTime) / 1000);
this.minutes = Math.floor(diffInSeconds / 60);
this.seconds = diffInSeconds - this.minutes * 60;
this.render();
this.updateSession();
},
utilities: {
pad: function pad(number) {
return number < 10 ? '0' + number : number;
}
},
container: function container() {
return $(document);
},
render: function render() {
this.container().find('#timer-minutes').text(this.utilities.pad(this.minutes));
this.container().find('#timer-seconds').text(this.utilities.pad(this.seconds));
},
updateSession: function updateSession() {
sessionStorage.setItem('timerStartedTime', this.startedTime);
},
clearSession: function clearSession() {
sessionStorage.removeItem('timerStartedTime');
},
restoreFromSession: function restoreFromSession() {
// Using sessionsStorage to make the timer persistent
if (typeof Storage == "undefined") {
console.log('No sessionStorage Support');
return;
}
if (sessionStorage.getItem('timerStartedTime') !== null) {
this.restoredFromSession = true;
this.startedTime = new Date(sessionStorage.getItem('timerStartedTime'));
}
},
start: function start() {
this.restoreFromSession();
this.stop();
this.started = true;
this.tick();
this.timerId = setInterval(this.tick.bind(this), 1000);
},
stop: function stop() {
this.started = false;
clearInterval(this.timerId);
this.render();
}
};
TTimer.start();
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
<h1>
<span id="timer-minutes">00</span> :
<span id="timer-seconds">00</span>
</h1>
Inspired by Bergi's answer I created the following complete non drifting timer. What I wanted was a way to set a timer, stop it, and do this simply.
var perfectTimer = { // Set of functions designed to create nearly perfect timers that do not drift
timers: {}, // An object of timers by ID
nextID: 0, // Next available timer reference ID
set: (callback, interval) => { // Set a timer
var expected = Date.now() + interval; // Expected currect time when timeout fires
var ID = perfectTimer.nextID++; // Create reference to timer
function step() { // Adjusts the timeout to account for any drift since last timeout
callback(); // Call the callback
var dt = Date.now() - expected; // The drift (ms) (positive for overshooting) comparing the expected time to the current time
expected += interval; // Set the next expected currect time when timeout fires
perfectTimer.timers[ID] = setTimeout(step, Math.max(0, interval - dt)); // Take into account drift
}
perfectTimer.timers[ID] = setTimeout(step, interval); // Return reference to timer
return ID;
},
clear: (ID) => { // Clear & delete a timer by ID reference
if (perfectTimer.timers[ID] != undefined) { // Preventing errors when trying to clear a timer that no longer exists
console.log('clear timer:', ID);
console.log('timers before:', perfectTimer.timers);
clearTimeout(perfectTimer.timers[ID]); // Clear timer
delete perfectTimer.timers[ID]; // Delete timer reference
console.log('timers after:', perfectTimer.timers);
}
}
}
// Below are some tests
var timerOne = perfectTimer.set(() => {
console.log(new Date().toString(), Date.now(), 'timerOne', timerOne);
}, 1000);
console.log(timerOne);
setTimeout(() => {
perfectTimer.clear(timerOne);
}, 5000)
var timerTwo = perfectTimer.set(() => {
console.log(new Date().toString(), Date.now(), 'timerTwo', timerTwo);
}, 1000);
console.log(timerTwo);
setTimeout(() => {
perfectTimer.clear(timerTwo);
}, 8000)
driftless is a drop-in replacement for setInterval that mitigates drift. Makes life easy, import the npm package, then use it like setInterval / setTimeout:
setDriftlessInterval(() => {
this.counter--;
}, 1000);
setDriftlessInterval(() => {
this.refreshBounds();
}, 20000);
you can use a function called setTimeout that we can use to set the countdown.
Firstly, create a javascript snippet and add it to your page as follows;
var remainingTime = 30;
var elem = document.getElementById('countdown_div');
var timer = setInterval(countdown, 1000); //set the countdown to every second
function countdown() {
if (remainingTime == -1) {
clearTimeout(timer);
doSomething();
} else {
elem.innerHTML = remainingTime + ' left';
remainingTime--; //we subtract the second each iteration
}
}
Source + more details -> https://www.growthsnippets.com/30-second-countdown-timer-javascript/
Many of these answers here are great, but they typically their code examples are pages and pages of code (the good ones even have instructions on the best way to copy/paste it all). I just wanted to understand this problem with a very simple example.
Working Demo
var lastpause = 0;
var totaltime = 0;
function goFunction(e) {
if(this.innerText == 'Off - Timer Not Going') {
this.innerText = 'On - Timer Going';
} else {
totaltime += Date.now() - lastpause;
this.innerText = 'Off - Timer Not Going';
}
lastpause = Date.now();
document.getElementById('count').innerText = totaltime + ' milliseconds.';
}
document.getElementById('button').addEventListener('click', goFunction);
<button id="button">Off - Timer Not Going</button> <br>
Seconds: <span id="count">0 milliseconds.</span>
Explanation of Demo
totaltime — This is the total time calculated.
lastpause — This is the only real temporary variable we have. Whenever someone hits pause, we set lastpause to Date.now(). When someone unpauses, and re-pauses again, we calculate the time diff of Date.now() subtracted from the last pause.
We only need those two variables: Our total and the last time we stopped the timer. The other answers seem to use this approach, but I wanted a compact explanation.
I gave up building my own and ended up using this neat library.
Below is the image element that is acting as the background. The position is absolute and it also has a low z-index so it stays behind the rest of the content.
<img src="day-sky.jpg" id="background" />
The secs below just refers to seconds in a minute. This is just for test purposes, but I'd like to have one background image if the seconds is < 30 and a different one if it's greater that 30. If possible the transition would be a nice fade to the next image.
I've been searching around for ways to do this but haven't come up with a good way to do it. Any thoughts?
function changeBackground() {
if (secs > 30) {
//have one background
}
else {
//have a different background
}
}
You might want to use setInterval() function to change the background after every time stamp you define as per your requirement.
setInterval(changebackground, timeout); runs the code/function once after the timeout.
$(function() {
setInterval(function() {
var bg = ["#000","#FF0", "#909"]
var rep= Math.floor(Math.random() *3);
$("body").css("background",bg[rep])
}, 3000)
})
Here's a working example: http://jsfiddle.net/PKqGk/
var imgs = [
"http://placehold.it/1920x1080/&text=1",
"http://placehold.it/1920x1080/&text=2",
"http://placehold.it/1920x1080/&text=3",
"http://placehold.it/1920x1080/&text=4",
"http://placehold.it/1920x1080/&text=5",
"http://placehold.it/1920x1080/&text=6"
],
ind = 0,
dur = 10 * 1000; // ten seconds
(function imgSlide(){
var img = ind % 2 ? $('#imageOne') : $('#imageTwo'),
hid = ind % 2 ? $('#imageTwo') : $('#imageOne');
console.log(img, hid);
img.fadeOut("slow", function(){
hid.fadeIn("slow").css('margin-left', -hid.width()/2);
if (++ind == imgs.length) ind = 0;
img.attr('src', imgs[ind]);
setTimeout(imgSlide, dur);
});
})();
My aim is to create identify a piece of code that increments a number by 1, every 1 second:
We shall call our base number indexVariable, I then want to: indexVariable = indexVariable + 1 every 1 second; until my indexVariable has reached 360 - then I wish it to reset to 1 and carry out the loop again.
How would this be possible in Javascript? - if it makes a difference I am using the Raphael framework.
I have carried out research of JavaScript timing events and the Raphael delay function - but these do not seem to be the answer - can anyone assist?
You can use setInterval() for that reason.
var i = 1;
var interval = setInterval( increment, 1000);
function increment(){
i = i % 360 + 1;
}
edit: the code for your your followup-question:
var interval = setInterval( rotate, 1000);
function rotate(){
percentArrow.rotate(1,150,150);
}
I'm not entirely sure, how your rotate works, but you may have to store the degrees in a var and increment those var too like in the example above.
var indexVariable = 0;
setInterval(function () {
indexVariable = ++indexVariable % 360 + 1; // SET { 1-360 }
}, 1000);
Try:
var indexVariable = 0;
setInterval(
function () {
indexVariable = (indexVariable + 1) % 361;
}, 1000}