How can I reload an image on a time interval? - javascript

I have two images that need to be reloaded in x time. I tried to do it this way:
<script>
function srcreload(){
imguser=document.getElementsByName("userimage")[0];
imgme=document.getElementsByName("me")[0];
imguser.src=imguser.src;imgme.src=imgme.src;setTimeout("srcreload()",15000);};
setTimeout("srcreload()",15000);
</script>
<img src="somesrc" name="userimage">
<img src="someothersrc" name="me">
Why isn't this working and how do I fix it? I got it to work one time, but then I must have changed something because it is no longer working.

Use var.
Don't pass a string to setTimeout, but a function.
Indent properly.
If you indent nicely, you see an extraneous }, which doesn't belong there.
var url = "...";
function srcreload() {
var imguser = document.getElementsByName("userimage")[0];
var imgme = document.getElementsByName("me")[0];
var random = "?" + Math.random();
imguser.src = url + random;
imgme.src = url + random;
setTimeout(srcreload, 15000);
}
setTimeout(srcreload, 15000);

imguser.src=imguser.src;
imgme.src=imgme.src;
does these do lines makes any sense, same value is being copied?

Related

Array image looping in JavaScript

I have been trying to loop traffic light images in JavaScript. I'm not sure what to do, can someone give advice.
A slight modification to your code. Here is a working sample.
I removed the dvi.count counter as it creates more confusion, We need to maintain the counters outside the function. I changed the logic to pass around the index of the image in the array starting from 0.
var image = new Array("red.jpg", "redamber.jpg", "green.jpg", "amber.jpg");
var timeout;
function stopIt() {
clearTimeout(timeout);
}
function changeimage (images, index) {
var dvi = document.getElementById(images);
if(image.length <= index)
index = 0;
dvi.src = image[index];
dvi.alt = image[index];
timeout = setTimeout('changeimage("' + images + '",' + (index + 1) + ')', 1000);
}
<body onload="changeimage('changer',0)">
<div>
<img src="t1" alt="test1" id="changer" />
</div>
</body>
I have made 3 changes to your code
Fixed the typeo div.count to dvi.count
Corrected the indenting and braces round the if statement (Not strictly necessary, but makes the code way more readable)
Replaced your nasty use of a string parameter in setTimeout to be a function reference
function changeimage(images){
var dvi=document.getElementById(images);
if(!dvi.count || dvi.count == image.length ){
dvi.count=0;
}
dvi.src=image[dvi.count];
dvi.alt=image[dvi.count];
dvi.count=dvi.count+1;
timeout=setTimeout(function(){
changeimage(images);
},3500);
}
Live example: https://jsfiddle.net/Lofug2hf/1/

Fade In don't work

I have wrote this javascript to show some images with id: imgFotogramma1/imgFotogramma2/ecc.. randomly in 8 different div with id Fotogramma1/Fotogramma2/ecc..:
function rullino() {
var immagini = new Array("strutture/1.jpg", "strutture/2.jpg", "strutture/3.jpg", "strutture/4.jpg", "strutture/5.jpg", "strutture/6.jpg", "strutture/7.jpg", "strutture/8.jpg", "strutture/9.jpg");
for (i = 1; i < 9; i++) {
var x = Math.floor(immagini.length * Math.random(1));
var imgId = "imgFotogramma" + i;
$(function () {
$(imgId).fadeIn(1000);
src = $(imgId).attr('src');
src = immagini[x];
alert(src);
});
}
setInterval("rullino()", 4000);
};
Now,this code start when body is loaded and its repeated every 4 seconds but i don't understand why the images are not displayed. I have started to work with Jquery not too much time ago and probably something are wrong.
I want to specify that: if i use normally javascript to assign to the src attribute the value of immagini[x],all work fine and the images are displayed.I have problem only to apply the fadein() motion.
I need a help to understand where is wrong,i have studied the fadeIn() API and i have tried to apply to my case.
Thanks in advance to anyone want to help me.
$(imgId).fadeIn(1000);
should be:
$('#'+imgId).fadeIn(1000);
Use # + idOfElemnt to select element with particular id.
You already doing it right. Just replace
var imgId = "imgFotogramma"+i;
With
var imgId = "#imgFotogramma"+i;
Since your are using the ID of the image, then your must have to use the "#" for id for applying the jQuery on it.
To select an ID, use # + elemID. Like this:
var imgId = "#imgFotogramma" + i;
Also, fade will not occur if the element is not hidden. First hide it, and then fade it in:
$(imgId).hide().fadeIn(1000);

Trying to get an image to show dependent on a result of a previous function

I am very new to javascript so please be very gentle and explain things as much as you can be bothered to please ;)
I am trying to create a button that will randomly select a name from a list and display it with an image of the person (hero if you know what this is for).
I have so far the a button that runs a function that selects the name randomly, I'm just having difficulty getting the image to show...
<html>
<body>
<button onclick="myFunction()">Random</button>
<script>
function myFunction()
{
var strings = ['Axe', 'Bane', 'Batrider' ];
var randomIndex = Math.floor(Math.random() * strings.length);
var randomString = strings[randomIndex];
document.write(' ' + randomString);
}
</script>
<script type="text/javascript">
var picData = [
['Axe','http://ponky.org/~ropedy/DC/icons/heroes/Axe.png'],
['Bane','http://ponky.org/~ropedy/DC/icons/heroes/Bane.png'],
['Batrider','http://ponky.org/~ropedy/DC/icons/heroes/Batrider.png']
];
window.onload=myFunction(){
var cookieValue = 'Axe';
for(i=0; i < picData.length; i++){
if(cookieValue == picData[i][0]) {
document.getElementById('imgCont').src = picData[i][1];
i=picData.length;
}
}
}
</script>
<div>
<img id="imgCont" src="" alt="" />
</div>
Change your window.onload to something like this:
window.onload = function() {
myFunction();
// then the rest of your stuff to set the .src
}
But it looks like what you actually want to do is move the stuff for setting the .src to a separate function so you can call it in response to your button click.
Something like:
var picData = [
['Axe','http://ponky.org/~ropedy/DC/icons/heroes/Axe.png'],
['Bane','http://ponky.org/~ropedy/DC/icons/heroes/Bane.png'],
['Batrider','http://ponky.org/~ropedy/DC/icons/heroes/Batrider.png']
];
function myFunction()
{
var randomIndex = Math.floor(Math.random() * picData.length);
var randomString = picData[randomIndex][0];
document.write(' ' + randomString); // Note: I'd generally avoid document.write
document.getElementById('imgCont').src = picData[randomIndex][1];
}
Now you can call this both from onload and onclick if you want to give you a random image when first loaded and a random image each time you click the button.
For easy to read and maintain code, I'd also replace your array or arrays with an array of object literals:
var picData = [
{name:'Axe', imageUrl:'http://ponky.org/~ropedy/DC/icons/heroes/Axe.png'},
{name:'Bane', imageUrl:'http://ponky.org/~ropedy/DC/icons/heroes/Bane.png'},
{name:'Batrider', imageUrl:'http://ponky.org/~ropedy/DC/icons/heroes/Batrider.png'}
];
Why? Because now instead of:
picData[randomIndex][1];
I can write:
picData[randomIndex].imageUrl;
Which is a lot more readable and makes it clearer what you are actually doing.

change image using javascript based on function result

I've been searching and trying to figure this out for hours but i seem to be missing something. Basically i'm trying to make it so if i click a link/button it executes a script to increase or decrease the number by a specified amount in a function. (in this example its by 1)
The image files that im trying to display are supposed to change depending on the final result. but the image never changes.
any suggestions are greatly appreciated
<script type="text/javascript">
var p1hps = 20;
var p1hpimage
function p1p1Click() {
p1hps = (p1hps +1);
function p1health(){
};
}
function p1health() {
p1hpimage = "images/p1" + p1hps + ".png";
document.getElementById('p1hp').src = p1health();
}
</script>
<body>
<img src="images/p1p1.png" width="165" height="87" alt="">
<img src="images/p120.png" id="p1hp" width="324" height="252" alt="">
</body>
You need to invoke the p1health function inside p1p1Click, instead you were declaring another function with the name p1health inside p1p1Click.
Also the images src property, you need to assign the value of the variable p1hpimage instead of recursively calling the p1health method
var p1hps = 20;
function p1p1Click() {
p1hps++;
p1health();
}
function p1health() {
var p1hpimage = "images/p1" + p1hps + ".png";
document.getElementById('p1hp').src = p1hpimage ;
}
Demo: Fiddle -- inspect the source with dev tools to see the src getting updated
Try this :
var _myPicArray =new Array("pic1.png","pic2.png","pic3.png");
function p1health(n) {
document.getElementById('p1hp').src = myPicArray[n] ;
}

jQuery won't load updated images

Is anyone able to determine, how to stop the jQuery caching the image that it grabs, and displaying the same image around and around again?
Basically the image is been re-uploaded every 5 seconds, as it acts as a webcam (if you check the time stamp on the bottom right of the image, you can tell if it's been updated or not)
http://colourednoise.co.uk/scripts/index.htm
Thank you
(sorry I forgot to hit paste for the code)
$(function(){
$(document).ready(function() {
var imgs = ['http://www.ramseycommunityradio.co.uk/images/webcam.jpg', 'http://www.ramseycommunityradio.co.uk/images/webcam.jpg']
$("#webcam").attr('src', imgs[1]);
var refreshId = setInterval(function() {
$("#webcam").fadeOut("slow", function() {
var $el = $(this);
$el.attr('src', $.inArray($el.attr('src'), imgs) === 0 ? imgs[1] : imgs[0]);
$el.fadeIn("slow");
});
}, 2000);
});
You could try appending a changing query string onto the URL, this should stop caching if that is indeed your problem. I've seen this done with a time stamp here: how to generate and append a random string using jquery
So each time you generate an image you do:
var qs = (new Date).getTime();
var url = 'http://www.example.com/images/myimage.jpg?' + qs;
$(el).attr('src',url);
your code:
var imgs = ['http://www.ramseycommunityradio.co.uk/images/webcam.jpg', 'http://www.ramseycommunityradio.co.uk/images/webcam.jpg']
$("#webcam").attr('src', imgs[1]);
var refreshId = setInterval(function() {
$("#webcam").fadeOut("slow", function() {
var $el = $(this);
$el.attr('src', $.inArray($el.attr('src'), imgs) === 0 ? imgs[1] : imgs[0]);
// this condition is redundant, it will ultimately give the same result always
// because imgs[0]==imgs[1]
$el.fadeIn("slow");
});
}, 2000);
as far a JQuery is concerned you are not changing the SRC attribute (JQuery knows nothing about the content of the image). Try using two different names in the server-side like webcam0.jpg and webcam1.jpg and alternating between them.
One trick is t append a random query string URL which causes the image to reload from the server. The code could be something like:
setInterval(function() {
var img = $("#img").get(0);
img.src = img.src.replace(/\?.*/, "") + "?" + Math.random();
}, 5000);

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