Develop Reference

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">

Javascript array is not recognizing called variable

function slideShow() {
var pageSplash = document.getElementById('splash');
var image = ["pic1.jpg", "pic2.jpg", "pic3.jpg", "pic4.jpg"];
var i = 0;
while (i <= image.length) {
if (i > image.length) {
i = 0;
}
i += 1;
pageSplash.innerHTML = '<img id ="splashImage" src="file:///C:/JonTFS/JonGrochCoding/Javascript%20Practical%20Test/' + image[i] + '">';
setTimeout('slideShow', 5000);
}
}
I'm unsure why my i variable is not being recognized as the i variable from the rest of the function, so when ever I try to run my while loop it get's an error message saying that it's undefined.

I think you want setInterval instead of setTimeout, and you want you be careful that you increment i after you you update innerHTML.
function slideShow() {
var pageSplash = document.getElementById('splash');
var image = ["pic1.jpg", "pic2.jpg", "pic3.jpg", "pic4.jpg"];
var i = 0;
setInterval(function () {
if (i === image.length) {
i = 0;
}
pageSplash.innerHTML = '<img id ="splashImage" src="file:///C:/JonTFS/JonGrochCoding/Javascript%20Practical%20Test/' + image[i] + '">';
i++;
}, 5000)
}
slideShow();

You don't need a while loop. You don't need to reset i. You don't need to set innerHTML.
Click Run code snippet... to see how this works. More explanation below the code
function slideShow(elem, images, delay, i) {
elem.src = images[i % images.length];
setTimeout(function() {
slideShow(elem, images, delay, i+1);
}, delay);
}
// setup slideshow 1
slideShow(
document.querySelector('#slideshow1 img'), // target element
[ // array of images
'http://lorempixel.com/100/100/animals/1/',
'http://lorempixel.com/100/100/animals/2/',
'http://lorempixel.com/100/100/animals/3/',
'http://lorempixel.com/100/100/animals/4/',
'http://lorempixel.com/100/100/animals/5/',
'http://lorempixel.com/100/100/animals/6/'
],
1000, // 1000 ms delay (1 second)
1 // start on slide index 1
);
// setup slideshow 2
slideShow(
document.querySelector('#slideshow2 img'), // target element
[ // array of images
'http://lorempixel.com/100/100/nature/1/',
'http://lorempixel.com/100/100/nature/2/',
'http://lorempixel.com/100/100/nature/3/',
'http://lorempixel.com/100/100/nature/4/',
'http://lorempixel.com/100/100/nature/5/',
'http://lorempixel.com/100/100/nature/6/'
],
500, // 500 ms delay
1 // start on slide 1
);
#slideshow1, #slideshow2 {
width: 150px;
display: inline-block;
}
<div id="slideshow1">
<h2>Animals</h2>
<p>(1000 ms delay)</p>
<!-- initial image -->
<img src="http://lorempixel.com/100/100/animals/1/">
</div>
<div id="slideshow2">
<h2>Nature</h2>
<p>(500 ms delay)</p>
<!-- initial image -->
<img src="http://lorempixel.com/100/100/sports/1/">
</div>
This is a huge improvement because your slideshow function is reusable. It means you can use the same function for any slideshow you want. You can even run multiple slideshows on the same page, as I have demonstrated here.

As others have pointed out, the while loop is unnecessary and, as I pointed out, the setTimout was incorrectly written. The following simplifies your code significantly:
var i = 0;
function slideShow() {
var pageSplash = document.getElementById('splash');
var imageArray = ["pic1.jpg", "pic2.jpg", "pic3.jpg", "pic4.jpg"];
if(i < imageArray.length) {
pageSplash.innerHTML = '<img title='+ imageArray[i] + ' id ="splashImage" src="file:///C:/JonTFS/JonGrochCoding/Javascript%20Practical%20Test/' + imageArray[i] + '">';
}
i++;
}
setInterval(slideShow, 2000);
See: https://jsfiddle.net/dauvc4j6/8/ for a working version.

setTimeout calls the function again so you're re-initializing i to 0 every time you call it. Since you can use setTimeout to call the function recursively you don't need the while loop. Pull i out of the function altogether and make it a global variable.
//i should be global
var i = 0;
function slideShow() {
var pageSplash = document.getElementById('splash');
var image = ["pic1.jpg", "pic2.jpg", "pic3.jpg", "pic4.jpg"];
if (i >= image.length) {
i = 0;
}
i += 1;
pageSplash.innerHTML = '<img id ="splashImage" src="file:///C:/JonTFS/JonGrochCoding/Javascript%20Practical%20Test/' + image[i] + '">';
//set timeout is going to call slideShow again so if it's in the function it will call recursively, if you wanted to stop after a certain point you could nest setTimeout in an if
setTimeout(slideShow, 5000);
}
//you need to initially call the function
slideShow();

Javascript show imgs one by one with interval

I have the below images and I'm trying to show them one by one by interval of 3 seconds, but I am not able to get it work. It continues to stay on 0 and does not show the image, help would be nice:
<img src="one.png"></img>
<img src="two.png"></img>
javascript :
window.animate = function(){
var timer = '';
var imgs = document.getElementsByTagName('img');
for (var i = 0; i < imgs.length; i++) {
var timer = setInterval(function(){
alert(i);
imgs[i].style.display = 'block';
}, 3000);
if(i == imgs.length){
clearInterval(timer);
}
}
}

This might be what you're looking for:
window.animate = function(){
var imgs = document.getElementsByTagName('img');
var index = 0;
var timer = setInterval(function() {
// Hide all imgs
for (var i = 0; i < imgs.length; i++)
imgs[i].style.display = 'none';
// Display next img
imgs[index].style.display = 'block';
index++;
// Stop after all displayed.
if (index >= imgs.length)
clearInterval(timer);
}, 3000);
}

Here is one way to do it:
Fiddle: http://jsfiddle.net/aecuappp/
HTML:
<img src="http://placehold.it/350x150"></img>
<img src="http://placehold.it/350x150"></img>
<img src="http://placehold.it/350x150"></img>
<img src="http://placehold.it/350x150"></img>
<img src="http://placehold.it/350x150"></img>
<img src="http://placehold.it/350x150"></img>
JS:
var imgs = document.getElementsByTagName('img');
var interval = 3000;
for (var i = 0; i < imgs.length; i++) {
(function (index, time) {
setTimeout(function() {
imgs[index].style.display = 'block';
}, time);
} (i, interval));
interval = interval + 3000;
}
CSS:
img {
display: none;
}
Basically you can start interval at 0 if you want first image to show up immediately. And each time it adds 3 seconds to the timeout since these are all created roughly at the same time. I wrapped the setTimeout in an IIFE to give interval and index scope for when the timeout needs the values at the time we created the timeout.

Since these are essentially all timing out at the same time, you need to implement a callback pattern to your interval to trigger the next one, or you need to increase the interval per index; i.e. set the timer's interval to 3000*(i+1), which will effectively trigger the next one at the delay plus the previous delay. This does not account for the actual images load however. Additionally, I would consider using setTimeout since you only need to do this once.
var img = $('img.targets');
for (var i=0;i<img.length;i++) {
var duration = 3000;
setTimeout( function() {
// do dom work here
}, duration*(i+1));
}

You can accomplish this by queuing up some timeouts using setTimeout and then making sure you are correctly passing the value of i to the function within. You can do that easily by using forEach instead of a regular loop:
window.animate = function() {
var imgs = document.getElementsByTagName('img');
imgs.forEach(function(img, i) {
setTimeout(function() {
img.style.display = 'block';
}, (i + 1) * 3000);
});
};

Change img src every second using Jquery and Javascript

I have been trying to write a script that changes an image src every two seconds based on a list.
So, everything is inside a forloop that loops over that list:
$(document).ready(function() {
var lis = {{dias|safe}}; <----- a long list from django. This part of the code works fine.
for (i=0; i<lis.length; i++){
src_img = lis[i][1];
var timeout = setInterval(function(){
console.log(src_img)
$("#imagen").attr("src", src_img);
}, 2000)
}
});
It doesn't work, the console logs thousands of srcs that correspond to the last item on the list. Thanks a lot for your help.

you don't need to run cycle in this case, you just save "pointer" - curentImage and call next array item through function ever 2 sec
var curentImage = 0;
function getNextImg(){
var url = lis[curentImage];
if(lis[curentImage]){
curentImage++;
} else {
curentImage = 0;
}
return url;
}
var timeout = setInterval(function(){
$("#imagen").attr("src", getNextImg());
}, 2000)

var curentImage = 0;
var length = lis.length;
function NewImage(){
var url = lis[curentImage];
if(curentImage < length){
currentImage++;
}
else{
currentImage = 0;
}
return url;
}
var timeout = setInterval(function(){
$("#imagen").attr("src", getNextImg());
}, 2000)
PS: Better than the previous one, Checks for lis length and starts from first if you reach end.

You need something like this
$(document).ready(function() {
var index = 0;
setInterval(function(){
src_img = lis[index++ % lis.lenght][1]; // avoid arrayOutOfBounds
$("#imagen").attr("src", src_img);
}, 2000)
});

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() { ... }
});