setInterval Speed Up | Javascript - javascript

I'm trying to gradually depreciate the interval in which the function inside a setinterval function is executed
Here's abstracted code for principle:
var speed = 100;
window.setInterval( speed-= 0.01 , speed);
Am I correct in believing the value for speed is taken once, on the first execution of setInterval and used, instead of being taken at every execution.
If so, how can I get around this? I verified this by setting the interval to 1000 and setting the "speed-=" to 999, and then printing the value for speed.
The value jumped from 1000 to 1 but then kept going down by 999, and even after the value became negative the functions inside setinterval were executed every 1 second.

An example of recursive call of setTimeout with changing interval.
function go() {
var node = document.createElement('div');
node.innerHTML = speed.toFixed(2);
document.body.appendChild(node);
if (speed > 1) {
setTimeout(go, speed);
}
speed *= 0.9;
}
var speed = 100;
go();

Related

How to smoothly increase a number to Y in X milliseconds exponentially

I'm making a semi-realistic 'physics' engine in node.js, if you can even call it that and I want to accelerate exponentially. E.g. from 0m/s to 4.5m/s in 2 seconds, then maybe decelerate to 0m/s in 3 seconds. Obviously for the deceleration part I can probably get away with inputting a negative number.
Here's a picture of what I'm thinking of, not sure if what I expect in the graph is the same thing as exponents.
I don't have any code, I thought I could base it off something like setInterval, but that would be linear.
You're right SetInterval can only provide with a fixed speed whereas what you need is dynamic speed.
One way is to make two arrays with an equal number of items. With first array named duration and second name speed. The variable Y will be changed by the speed for the duration corresponding to the # of the speed. See here :
var Y = 0; // The variable that is to be changed
var speed = [4.5, 0, -4.5]; // The acceleration in m/s
var time = [2, 4, 2]; // Duration corresponding to each acceleration in s
var sec = 1000; // 1 second = 1000 milliseconds
var i = 0; // A counter to remember the item number in the arrays
var dur = 0; // A variable to hold the duration for which a particular speed has currently lasted. This variable helps to validate the duration for which the Y is changed.
// The function that holds the logic
function tick() {
// Checking if duration is equal to or has crossed the user specified duration for the speed
if(dur >= time[i]*1000){
// If yes, move on to the next speed and duration
i++;
dur = 0;
if(i > speed.length-1){clearInterval(loop);} // If there are no more items in the array stop the interval
}
else {
// If not, continue increasing Y and dur
Y = Math.round(Y*1000 + (speed[i]/50)*1000)/1000 // A simple workaround to avoid the error in arthimetic calculation that occurs while using floats (decimal numbers) in JS.
console.log(Y); // This line is only for debugging purposes. IT CAN BE REMOVED
dur += sec/50;
}
}
var loop = setInterval(tick, sec/50);

Creating a Countdown with JavaScript

I am trying to make a Countdown that just log in the terminal the seconds remaining. It should be an interval of 1 second between every log. It has to be as a method of an object. I don´t know if it's because of the scope but somehow it's not working after many trials and code-rewriting.
Anybody can help me with this?
var Countdown = function(seconds) {
this.counter = seconds;
this.start = function() {
setTimeout(
function() {
while (this.counter >= 0) {
console.log(this.counter);
this.counter -= 1;
}
},1000)
}
}
I would use a setInterval() for a simple countdown timer. I would also write my function for the math loop outside of the setInterval and then call on the function within the interval, like the following => setInterval(timerFunction(), 1000). There is no need for a loop when you use the interval, it does the looping each defined time increment as set in your setInterval(). Each time the interval fires, the function will do its thing.
EDIT: added a conditional to see if the interval time has run out.
I have included an example of a simple count down timer in my answer below along with notation inside the code that helps to explain further. Hope this helps.
Also, by terminal, I assume you mean the console? My example displays the setInterval in the console...
let sMin = 2; // amount of minutes you wish to start with
let time = sMin * 60; // format for minutes by multiplying by 60 as we have 60 seconds in each minute
let countdown = setInterval(update, 1000) // set up a setInterval for the countdown function
// create a function that will countdown the seconds
function update() {
// define our minutes using Math.floor(time / 60)
let min = Math.floor(time / 60);
// define our seconds by modulating time with 60, our seconds units
let sec = time % 60;
// tenerary conditional to see if seconds is set to 0 for proper display of formatting as seconds
sec = sec < 10 ? '0' + sec : sec;
// display the countdown timer in time format using the minutes and seconds variables
console.log(`${min}:${sec}`);
// decrement time by one second with each interval as set in the setInterval call `1000`
time--;
// clear the interval if the minutes and seconds are both set to 0
min == 0 && sec == 0 ? clearInterval(countdown) : countdown;
}
Yes it was because of the scope. As you are using this inside setTimeout() it uses the global scope.
var Countdown = function(seconds) {
this.counter = seconds;
this.start = function() {
setTimeout(
function() {
while (this.counter >= 0) {
console.log(this.counter);
this.counter -= 1;
}
}.bind(this),1000)
}
}
I'm using bind to set "this" to current context.
And with reference to your question about timeout, instead of using setTimeout() use setInterval() to achieve your need about log with respect to seconds
function countDown(whileCountingDown, forHowLong, whenFinishedThen){
//error handling begin(for user's understanding)
if(arguments.length<3){return RangeError("ALL three arguments must be used")}
var typeErrors=[]
if(typeof whileCountingDown!="function"){typeErrors.push("whileCountingDown MUST be a function")}
if(typeof forHowLong!="number"){typeErrors.push("forHowLong MUST be a number(and it represents seconds)")}
if(typeof whenFinishedThen!="function"){typeErrors.push("whenFinishedThen MUST be a function")}
if(typeErrors.length>0){return TypeError(`There are ${typeErrors.length} parameters that are incorrect data types\n\n${typeErrors.join('\n')}`)}
//error handling begin(for user's understanding)
//........................................................................................................................
//the part that matters to you once you enter correct stuff
var i=setInterval(()=>{forHowLong--
if(forHowLong<=0){//count finished, determine what happens next
clearInterval(i); whenFinishedThen()
}
else{whileCountingDown(forHowLong)}//do this for each second of countdown
},1000)
}
console.log("The timers in the console and on the html element are 2 DIFFERENT countdowns")
//example use
countDown((m)=>{console.log(`${m} seconds left`)}, 30, ()=>{console.log('Cheers, the countdown is OVER')})
//obviously you can do stuff like edit randomHTML-Element.innerText for each second of the countdown or anything as you so desire since what i made is kindof flexible
//..........................................................................................................................
//more examples
//now for some fun stuff, we're gonna be editing an html structure, but first, we're going to make a 'timeParse' function to make it look kind of elegant
function timeParse(seconds){
//yup, error handling begin
if(typeof seconds!="number"){return TypeError("The parameter 'seconds' MUST be a number")}
//yup, error handling end
//below is the stuff to look at
var timeArr=[seconds]
if(timeArr[0]>=60){//if seconds >= 1 minute
timeArr.unshift(Math.floor(timeArr[0]/60))
timeArr[1]=timeArr[1]%60
if(timeArr[0]>=60){//if minutes >= 1 hour
timeArr.unshift(Math.floor(timeArr[0]/60))
timeArr[1]=timeArr[1]%60
if(timeArr[0]>=24){//if hours >= 1 day
timeArr.unshift(`${Math.floor(timeArr[0]/24)}d`)
timeArr[1]=timeArr[1]%24
}
}
}
return(timeArr.join`:`)
}
//now for applying countDown to things other than the console
function countDownAgain(){//just something that will show the flexibility of what i made.. im going above and beyond because i wanna look back on my answers as notes on how to do things(also ez copy pasting for future me xD)
countDown(
(s)=>{document.getElementById('toTime').innerText="Second Count "+timeParse(s)},
86401,
()=>{document.getElementById('toTime').innerText="No way you waited that long LOL"}
)
}
countDown(
(s)=>{document.getElementById('toTime').innerText="First Count "+timeParse(s)},
100,
countDownAgain
)
<div style="background-color:red;height:100px;text-align:center;line-height:50px"><h1 id="toTime">Count Down Time :}</h1></div>

Skip a setInterval every X loop?

I have a function that gets triggered every 10 seconds with a setInterval(); loop, and I'd like it to skip a call every 60 seconds. So the function would be executed at 10s, 20s, 30s, 40s and 50s but wouldn't be called at 60s, then gets called at 70s and so on.
Is there any straightforward way to do this, or do I have to tinker with incrementing a variable?
Thanks!
Do like this, use the simple modulo math and a counter.
var count = 0;
var interval = setInterval(function(){
count += 1;
if(count % 6 !== 0) {
// your code
}
}, 10000);

Javascript wait for one animation to finish before the next one begins

I have a Javascript function (Not jQuery) that animates a box opening or closing. The problem is that I close the box, run some code that changes the content, and then reopen it.
Now the "problem" is that the rest of the code is too fast, and so it never even manages to close, let alone reopen. I could make the animation not be allowed to run again internally unless the last one was finished, but this would limit it if I say, were to want to run it twice on two different objects.
So what's the best method to prevent this? My thought was possibly a timeout that says to wait before running the animation, but that seems hacky, an I wasn't sure if there was a better solution?
Thanks.
function animate(boxID, step, limit, speed){
// Add timeout property to animate function/object if it doesn't exist already
if(animate.timeout == undefined) animate.timeout = 0;
// Clear the current timeout
clearTimeout(animate.timeout);
// Initialize box and current box height
var box = document.getElementById(boxID);
var h = box.clientHeight;
// Check if we want the step needs to be changed to pos/neg based on which direction is wanted to be going
if(h < limit && step < 0 || // Positive
h > limit && step > 0){ // Negative
step *= -1;
}
// If the step is positive, then we need to be below the limit, or if negative, then greater than the limit
if((step > 0 && h <= limit - step) || (step < 0 && h >= limit - step)){
// Set new height
box.style.height = h + step + "px";
// Start new timeout
animate.timeout = setTimeout(function(){ animate(boxID, step, limit, speed, 1); }, speed);
}
else{
box.style.height = limit + "px"; // Set to the exact height
}
}
You could achieve this with a callback. Your animate function gets a plus parameter, a function to call when the animation is ready:
function animate(boxID, step, limit, speed, onReady){
When the animation is done, you call it:
else{
box.style.height = limit + "px"; // Set to the exact height
if (onReady) { onReady(); }
}
You also want to forward the callback to the timeout call:
setTimeout(function(){ animate(boxID, step, limit, speed, 1, onReady); }, speed);
So, you can call the function for multiple boxes like this:
animate(box1_id, close_step, close_limit, close_speed, function () {
// now box1 is closed, put something in. then:
animate(box1_id, open_step, open_limit, open_speed, null);
});
// then the same for box2, etc…
This way box1 and box2 will close simultaneously, and only reopen after the thing have been put inside.
Also, you can't store the timer on the function, because now it's running on multiple boxes. So you may store it on the boxes, or a separate place instead. For example create an object outside of the function and put all the boxes' timers in that:
var timeouts = {};
timeouts[box1_id] = setTimeout(…);

How to produce a time delay in JavaScript for a chat App?

I'm currently a beginner at JavaScript and predominantly code in Java.
My Question is is regarding invoking the document.write("string here") periodically (every 1/2 seconds) to append any new unprinted chat message to the client. I earlier tried using the following code :
<html>
<body onload="yantra();">
<script type="text/javascript">
x = 0;
function yantra(){
document.write("Hello<br>");
i = 1;
for(i = 0; i < 100; i++){
setTimeout("writeOneNum()", 1000);
}
}
function writeOneNum(){
x =x + 1;
document.write(x+"<br>");
}
function blank(){}
</script>
</body>
</html>
Instead of it printing 1 to 100 every 1000 millisecond as I expected it to print; in actuality, it printed 1 to 100 at one go (meaning without any delay).
Well, you are setting all the timeouts at once, so of course it fires them all at once. Your code will work with small modification to the loop:
function yantra(){
document.write("Hello<br>");
i = 1;
for(i = 0; i < 100; i++){
setTimeout("writeOneNum()", 1000 * i);
}
}
By multiplying the time with i, the first is fired instantly, the second at 1000 * 1 = 1000 ms, the third at 1000 * 2 = 2000 ms etc.
In your case, it could be wiser to consider the setInterval function:
function yantra(){
document.write("Hello<br>");
setInterval("writeOneNum()", 1000);
}
That will fire the writeOneNum() every second infinitely. To stop the interval at some point, take a look at clearInterval on that same link above.

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