Develop Reference

Autoplay in slider with js

let left = document.querySelector('.left');
let right = document.querySelector('.right');
let img = document.querySelector('.imgs');
let imgs = document.querySelectorAll('img');
let index = 0;
function rightimg() {
right.addEventListener('click', function () {
index++;
if (index > imgs.length - 1) {
index = 0;
}
img.style.transform = `translateX(${-index * 500}px)`;
console.log(img);
});
}
// setInterval(rightimg, 2000);
left.addEventListener('click', function () {
index--;
if (index < 0) {
index = imgs.length - 1;
}
img.style.transform = `translateX(${-index * 500}px)`;
console.log(img);
});
Hi friends,
I want to make autoplay image in this slider but setInterval is not working,
can you say what is wrong in here?
Thank you

Your function adds an eventlistener but it will only work when there will be an event(which is click in this case)
You can use swiperjs, it has many types of features and framework/library implentations. https://swiperjs.com/swiper-api

How can I reuse a function properly?

I try to make 3 basic slideshow.
I made this code for the first one and wanted to use it on the other 2 as well with the New slideS() method and with some parameter changing.But it's not working,even the first function is'nt working if I put parameter in it.
Can somebody explain me why is this not working and how to fix it?Thanks beforehand!
var img = document.getElementById("asd");
var imgArr = ["1.jpg", "3.png", "3.png"];
var i = 0;
function slideS(a) {
a.src = imgArr[i];
if (i < imgArr.length - 1) {
i++;
} else {
i = 0;
}
setTimeout("slideS()", 1500);
}
slideS(img)

You could do something like this, using an object oriented approach:
function SlideShow(el, imagesArray, msDelay) {
this.el = el;
this.images = imagesArray;
this.delay = (msDelay) ? msDelay : 1000;
this.timer = null;
this.Run = function () {
var self = this;
var index = 0;
this.timer = setInterval(function(){
self.el.src = self.images[index++ % self.images.length];
}, this.delay);
}
this.Stop = function() {
this.timer = null;
}
}
var img = document.getElementById("asd");
var imgArr = ["1.jpg", "3.png", "3.png"];
var delay = 1500;
var ss = new SlideShow(img, imgArr, delay);
ss.Run();
...
ss.Stop();
Would that work for you? Then you are using pure functions and an object that can be used to start, stop, and manage any slide show.

I think you want like:
Remove setTimeout. And use setInterval:
setInterval(function(){
slideS(img)
},1500)

You could use a closure over the element and the array and use setInterval instead of setTimeout.
function slide(id, array) {
function swap() {
image.src = array[i];
i++;
i %= array.length;
}
var image = document.getElementById(id),
i = 0;
setInterval(swap, 1500);
}
slide('image1', ['http://lorempixel.com/400/200/', 'http://lorempixel.com/400/200/', 'http://lorempixel.com/400/200/']);
<image id="image1"></image>

I assume it works when the function doesn't take a parameter?
Then, the reason it would work with no parameter, but stop working with a parameter, is that the setTimeout tries to recursively call the function but doesn't pass a parameter. So you'd change that to
setTimeout(() => {slideS(a);}, 1500);
But then when you try to run multiple instances of this concurrently, you'll get into trouble because your'e using global variables. You'll need to use something more local (perhaps closures?) for your lcv, for example.

try this... you are making mistake at some places
var img = document.getElementById("asd");
var imgArr = ["1.jpg", "3.png", "3.png"];
var i = 0;
function slideS(a) {
a.src = imgArr[i];
if (i < imgArr.length - 1) {
i++;
} else {
i = 0;
}
setTimeout(() => slideS(a), 1500);
/* you need to pass function to setTimeout and pass refrence of image that's 'a' */
// or use function instead of arrow function
setTimeout(function() { slides(a) }, 1500);
}
slideS(img)
hope this helps..

You have to use setInterval instead of setTimeout
var img = document.getElementById("asd");
var imgArr = ["https://i.stack.imgur.com/lgt0W.png", "https://i.stack.imgur.com/X0fKm.png", "https://i.stack.imgur.com/YfPSD.png"];
var i = 0;
function slideS(a) {
a.src = imgArr[i];
if (i < imgArr.length - 1) {
i++;
} else {
i = 0;
}
}
slideS(img); //initial call to start it without having to wait for 1500 ms to pass
setInterval(function() {
slideS(img);
}, 1500);
<img id="asd">

Preload image with Javascript and CSS

I have a big problem with images in javascript embedded aplications. I want make a preload image but I don't know how the browser works.
See this simple example: code
var colors = [
"http://www.robolaranja.com.br/wp-content/uploads/2014/10/Primeira-imagem-do-filme-de-Angry-Birds-%C3%A9-revelada-2.jpg",
"http://imguol.com/c/noticias/2013/12/13/13dez2013---esta-imagem-mostra-a-nebulosa-de-caranguejo-um-iconico-remanescente-de-supernova-na-nossa-galaxia-vista-do-observatorio-espacial-herschel-e-do-telescopio-hubble-uma-nuvem-de-gas-e-poeira-1386961235961_956x500.jpg",
"http://wallpaper.ultradownloads.com.br/121350_Papel-de-Parede-Imagem-Abstrata_1920x1200.jpg"
]
var currentDiv = "div2";
var count = 0;
var lenght = colors.length;
var timeForNextImage = 0;
var preloadOk = false;
setInterval(function() {
count ++;
if (count > lenght) count = 0;
var date = new Date();
var time = date.getTime();
if (time > (timeForNextImage - 3000) && preloadOk == false) {
preLoad();
} else if (time > timeForNextImage) {
play();
}
}, 300);
var play = function() {
if (currentDiv == "div2") {
$('#'+currentDiv).css("visibility", "visible");
} else {
$('#div2').css("visibility", "hidden");
}
var date = new Date();
timeForNextImage = date.getTime() + 10000;
preloadOk = false;
$("#lbl").text("div atual: "+currentDiv);
};
var preLoad = function() {
if (currentDiv == "div1") {
currentDiv = "div2";
} else {
currentDiv = "div1";
}
$("#" + currentDiv).css("background-image", 'url('+colors[count]+')');
preloadOk = true;
};
How you can look, I do a preload, in theory.. but, the browser only processes my image when I put it in the stage ?
What if I change the z-index attribute, it renders again?

You return preloadOK = true but the image doesn't load. That's not a preloader.
To make a preloader you can play with new Image() object or with load() event.
var images = new Array()
function preload() {
for (i = 0; i < preload.arguments.length; i++) {
images[i] = new Image()
images[i].src = preload.arguments[i]
}
}
preload(
"http://domain.tld/gallery/image-001.jpg",
"http://domain.tld/gallery/image-002.jpg",
"http://domain.tld/gallery/image-003.jpg"
)
See more
3 Ways to Preload Images with CSS, JavaScript, or Ajax

A simple way to preload an image is to just create an image tag and set the url as the src. You don't have to attach it to the DOM to make the request.
var preLoad = function() {
var img = new Image();
img.src = colors[count];
};

Execute function IF another function is complete NOT when

I am having trouble creating a slider that pauses on hover, because I execute the animation function again on mouse off, if I flick the mouse over it rapidly (thereby calling the function multiple times) it starts to play up, I would like it so that the function is only called if the other function is complete, otherwise it does not call at all (to avoid queue build up and messy animations)
What's the easiest/best way to do this?
$(document).ready(function() {
//get variables
var slide_width = $('.slider_container').width();
var number_of_slides = $('.slider_container .slide').length;
var slider_width = slide_width*number_of_slides;
//set element dimensions
$('.slide').width(slide_width);
$('.slider').width(slider_width);
var n = 1;
$('.slider_container').hover(function() {
//Mouse on
n = 0;
$('.slider').stop(true, false);
}, function() {
//Mouse off
n = 1;
if (fnct == 0) sliderLoop();
});
//Called in Slide Loop
function animateSlider() {
$('.slider').delay(3000).animate({ marginLeft: -(slide_width * i) }, function() {
i++;
sliderLoop();
});
}
var i = 0;
var fnct = 0
//Called in Doc Load
function sliderLoop() {
fnct = 1
if(n == 1) {
if (i < number_of_slides) {
animateSlider();
}
else
{
i = 0;
sliderLoop();
}
}
fnct = 0
}
sliderLoop();
});
The slider works fine normally, but if I quickly move my mouse on and off it, then the slider starts jolting back and forth rapidly...been trying to come up with a solution for this for hours now..

Here's what fixed it, works a charm!
$(document).ready(function() {
//get variables
var slide_width = $('.slider_container').width();
var number_of_slides = $('.slider_container .slide').length;
var slider_width = slide_width*number_of_slides;
//set element dimensions
$('.slide').width(slide_width);
$('.slider').width(slider_width);
var n = 1;
var t = 0;
$('.slider_container').hover(function() {
clearInterval(t);
}, function() {
t = setInterval(sliderLoop,3000);
});
var marginSize = i = 1;
var fnctcmp = 0;
//Called in Doc Load
function sliderLoop() {
if (i < number_of_slides) {
marginSize = -(slide_width * i++);
}
else
{
marginSize = i = 1;
}
$('.slider').animate({ marginLeft: marginSize });
}
t = setInterval(sliderLoop,3000);
});

get interval ID from else statement when set in IF

I am attempting to create a responsive slider, that will change to a simple set of dot points when in mobile mode (< 940).
The issue I am facing is in my else statement I am unable to clearintervals that were made in the if statement, because t comes up as undefined. I have resorted to using
for (var i = 1; i < 99999; i++) window.clearInterval(i); to clear the interval which works, but I don't like it because it's ugly and cumbersome, is there another way of accomplishing this?
$(document).ready(function() {
function rePosition() {
//get responsive width
var container_width = $('.container').width();
//Slider for desktops only
if(container_width >= 940) {
//get variables
var slide_width = $('.slider_container').width();
var number_of_slides = $('.slider_container .slide').length;
var slider_width = slide_width*number_of_slides;
//set element dimensions
$('.slide').width(slide_width);
$('.slider').width(slider_width);
var n = 1;
var t = 0;
$('.slider_container').hover(function() {
clearInterval(t);
}, function() {
t = setInterval(sliderLoop,6000);
});
var marginSize = i = 1;
//Called in Doc Load
function sliderLoop(trans_speed) {
if (trans_speed) {
var trans_speed = trans_speed;
}
else
{
var trans_speed = 3000;
}
if (i < number_of_slides) {
marginSize = -(slide_width * i++);
}
else
{
marginSize = i = 1;
}
$('.slider').animate({ marginLeft: marginSize }, trans_speed);
}
t = setInterval(sliderLoop,6000);
$('.items li').hover(function() {
$('.slider').stop();
clearInterval(t);
var item_numb = $(this).index();
i = item_numb;
sliderLoop(500);
}, function() {
t = setInterval(sliderLoop,6000);
});
}
else
{
for (var i = 1; i < 99999; i++)
window.clearInterval(i);
$('.slider').stop(true, true);
$('.slider').css('margin-left', '0px');
//rearrange content
if($('.slider .slide .slide_title').length < 1) {
$('.items ul li').each(function() {
var item_numb = $(this).index();
var content = $(this).text();
$('.slider .slide:eq(' + item_numb + ')').prepend('<div class="title slide_title">' + content + '</div>')
});
}
}
}
rePosition();
$(window).resize(function() {
rePosition();
});
});

Teemu's comment is correct. I'll expand on it. Make an array available to all of the relevant code (just remember that globals are bad).
$(document).ready(function() {
var myIntervalArray = [];
Now, whenever you create an interval you will need to reference later, do this:
var t = setInterval();//etc
myIntervalArray.push(t); //or just put the interval directly in.
Then to clear them, just loop the array and clear each interval.
for (var i=0; i<myIntervalArray.length; i++)
clearInterval(myIntervalArray[i]);
}

Umm, wouldn't t only be defined when the if part ran... as far as I can tell, this is going to run and be done... the scope will be destroyed. If you need to maintain the scope across calls, you'll need to move your var statements outside of reposition(), like so:
$(document).ready(function() {
var t = 0;
...
function rePosition() { ... }
});