I have two JS functions: a load() function that displays a progress bar and a kill () function that stops the execution of the load once the page is loaded.
Now when another page is loaded the progress bar is not displayed, knowing that the load function is called on every page.
Any hints on where the problem might be and if there is a way to fix it.
Here is my code:
<script type="text/javascript">
var count=0;
function load(i) {
j = parseInt(i);
document.getElementById("progressBar").style.display = "block";
count=count+1;
if (document.all) {
document.all.btn1.value=count+'%';
document.all.progressbar.pic1.width=2*count;
}
else {
document.getElementById("pic1").width=2*count;
document.getElementById("bar").width=count+'%';
}
if (count<100) {
setTimeout('load(j)',j);
}
if(count==100) {
document.getElementById("progressBar").style.display = "none";
count=0;
}
}
function kill(){
if (document.applets[0].isActive()) {
document.getElementById("progressBar").style.visibility = "hidden";
}
}
</script>
Thank you in advance !
In load() you're changing display to block, but in kill() you set visibility to hidden; you should set display to none instead, so it can properly be set to block again next time. Read about visibility.
Optimized code:
<script type="text/javascript">
var count = 0,
win = window,
doc = document,
progressBar = doc.getElementById("progressBar"),
t, j;
function load(i) {
j = parseInt(i);
progressBar.style.display = "block";
count++;
// no actual need to check if doc.all is available
// just select through id
doc.getElementById("pic1").style.width = 2*count;
doc.getElementById("bar").style.width = count+'%';
if (count < 100) {
t = win.setTimeout('load(j)',j);
} else {
progressBar.style.display = "none";
win.clearTimeout(t);
count = 0;
}
}
function kill(){
if (doc.applets[0].isActive()) {
progressBar.style.display = "none";
}
}
</script>
If you assign setTimeout to a variable, you can use clearTimeout on it to stop it.
E.g.
set the timeout with
t = setTimeout('load(j)',j);
then stop it with
clearTimeout(t); Let me know if that helps, and makes sense :)
Related
I want to create a JavaScript program who allow the user to switch between
image by using previous and next button. But i can't use window.onload to load the next image cause window.onload overwrite the previous window.onload. I want to know if their exist any solution to make window.onload work with two functions in the same time. If window.onload can't be usable for this kind of program you can suggest me another solution.
Thank you.
var i =0;
var image = [];
image[0]= 'image.jpg';
image[1]= 'image2.jpg';
image[2]= 'panther.jpg'
function next(){
document.slide.src = image[i];
if(i<image.length-1){
i++;
}
else{
i=0;
}
document.getElementById('bouton1').addEventListener('click',next);
}
function previous(){
document.slide.src = image[i];
if(i>0){
i--;
}
else{
i=image.length-1;
}
document.getElementById('bouton2').addEventListener('click',previous);
}
window.onload = next;
window.onload = previous;
Needed a couple of changes, can you test it like this. Note we changed the onload to attach listeners. See comment.
var i =0;
var image = [];
image[0]= 'image.jpg';
image[1]= 'image2.jpg';
image[2]= 'panther.jpg'
function next(){
document.slide.src = image[i];
if(i<image.length-1){
i++;
}
else{
i=0;
}
}
function previous(){
document.slide.src = image[i];
if(i>0){
i--;
}
else{
i=image.length-1;
}
}
// This is window.onload
(function(){
// Move calls to attach event listeners here
document.getElementById('bouton2').addEventListener('click',previous);
document.getElementById('bouton1').addEventListener('click',next);
})();
addEventListener is a better method for adding an event handler without replacing an existing one.
window.addEventListener('load', e => { /* ... */ });
As a rule of thumb, any on(blah) attributes in the DOM can be replaced with addEventListener(blah, ...).
I'm not exactly sure about your idea behind window.onload, if you want to preload images (so the user does not have to wait for the image to load on buttons click...) than you could use new Image() and something like:
const EL_slide = document.getElementById("slide");
const EL_prev = document.getElementById('prev');
const EL_next = document.getElementById('next');
const image = [
'//placehold.it/800x600/0bf?text=1',
'//placehold.it/800x600/f0b?text=2',
'//placehold.it/800x600/0fb?text=3'
];
const n = image.length;
let i = 0;
// Preload images
image.forEach(src => {
var img = new Image();
img.src = src;
});
// Animation logic
function anim() {
if((/prev|next/).test(this.id)) i = this.id === "next" ? ++i : --i;
i = i<0 ? n-1 : i%n; // Index fixer (prevents out of bound index)
EL_slide.style.backgroundImage = `url('${image[i]}')`
}
// Events
[EL_prev, EL_next].forEach(EL => EL.addEventListener('click', anim));
// Load first!
anim();
#slide {
height: 70vh;
transition: 0.3s;
background: none 50% 50% / cover no-repeat;
}
<button id="prev">←</button>
<button id="next">→</button>
<div id="slide"></div>
and just make sure to place your Javascript right before the closing </body> tag.
What I want:
There are two pictures that are being switched/swapped every three seconds.
I want to make it so that when the button is clicked, the picture switches and the auto-swap resets. So if the button is clicked, the image swaps and three seconds later, it will auto-swap, until the button is clicked again in which the cycle will repeat.
What I have right now
Currently, the problem is that: when the button is clicked, it messes up the timing of the auto-switches.
Edit:
Please don't create a new code base. Just modify mines. The code doesn't have to be an expert super concise level. I'm only three weeks into JavaScript (and it's my first programming language). I have to explain to classmates and it wouldn't be nice the code had elements I don't understand. So sorry for the inconvenience.
Right now I just need the button to correctly stop and restart the time.
<html>
<head>
<script>
let reset = setTimeout(change, 3000);
function change() {
if(document.getElementById("picture").src == "https://images.pexels.com/photos/248797/pexels-photo-248797.jpeg?auto=compress&cs=tinysrgb&h=350") {
document.getElementById("picture").src = "https://images.pexels.com/photos/67636/rose-blue-flower-rose-blooms-67636.jpeg?auto=compress&cs=tinysrgb&h=350";
}
else {
document.getElementById("picture").src = "https://images.pexels.com/photos/248797/pexels-photo-248797.jpeg?auto=compress&cs=tinysrgb&h=350";
}
setTimeout(change, 3000);
}
function fastChange() {
clearTimeout(reset);
if(document.getElementById("picture").src == "https://images.pexels.com/photos/248797/pexels-photo-248797.jpeg?auto=compress&cs=tinysrgb&h=350") {
document.getElementById("picture").src = "https://images.pexels.com/photos/67636/rose-blue-flower-rose-blooms-67636.jpeg?auto=compress&cs=tinysrgb&h=350";
}
else {
document.getElementById("picture").src = "https://images.pexels.com/photos/248797/pexels-photo-248797.jpeg?auto=compress&cs=tinysrgb&h=350";
}
}
</script>
</head>
<body>
<input type="button" onclick="fastChange();">
<img src="https://images.pexels.com/photos/248797/pexels-photo-248797.jpeg?auto=compress&cs=tinysrgb&h=350" id="picture">
</body>
</html>
The reason why your timer resets is because you are not clearing the timeout.
you need to make a reference to the timeout and then use clearTimeout() on it whne you make the fast change. I don't think it is possible or wise to do that inline the way you have it so you code needs to be refactored
let imgSrc1 = 'https://images.pexels.com/photos/248797/pexels-photo-248797.jpeg?auto=compress&cs=tinysrgb&h=350'
let imgSrc2 = 'https://images.pexels.com/photos/67636/rose-blue-flower-rose-blooms-67636.jpeg?auto=compress&cs=tinysrgb&h=350'
let imgElement = document.getElementById('picture');
let timeout;
function change() {
if(imgElement.src === imgSrc1) {
imgElement.src = imgSrc2;
} else {
imgElement.src = imgSrc1;
}
if (timeout) {
clearTimeout(timeout);
}
timeout = setTimeout(change, 3000);
}
You don't even need the second function fastChange. Now you can sent the onClick listener to change() like this
document.getElementById('whatever you want to click').onCLick = change;
Setting and clearing timeouts in multiple places will work, but I prefer using a "main loop" and a variable to count frames.
Here's an example that uses setInterval and resets a timer variable when the button was clicked:
const url1 = "https://images.pexels.com/photos/248797/pexels-photo-248797.jpeg?auto=compress&cs=tinysrgb&h=350";
const url2 = "https://images.pexels.com/photos/67636/rose-blue-flower-rose-blooms-67636.jpeg?auto=compress&cs=tinysrgb&h=350";
function change() {
picture.src = picture.src == url1 ? url2 : url1;
}
var timer = 0;
setInterval(function() {
timer++;
time.textContent = timer;
if (timer === 30) fastChange();
}, 100);
function fastChange() {
change();
timer = 0;
}
picture.src = url1;
swap.onclick = fastChange;
#picture {
height: 70vh
}
<button id="swap">SWAP</button> <span id="time"></span><br>
<img id="picture">
You can do this by calling setTimeout and updating the index as necessary. Just be sure to store the most recent timeout id so that it can be cancelled on reset using clearTimeout.
// store the reference to the <img> that contains the picture
const pic = document.getElementById('picture')
// store a list (array) of the two picture urls
const sources = [
'https://images.pexels.com/photos/248797/pexels-photo-248797.jpeg?auto=compress&cs=tinysrgb&h=350',
'https://images.pexels.com/photos/67636/rose-blue-flower-rose-blooms-67636.jpeg?auto=compress&cs=tinysrgb&h=350'
]
// used to store a reference to the interval timer you created.
var lastTimer
// a starting index of the list (i.e. which image we are up to right now)
var index = 1
// this functions swaps the image and sets a timer
function startRotation() {
// update the index to the next one (goes 0-1-0-1->etc)
index = 1 - index
// sets the .src of the image element
pic.src = sources[index]
// starts a 3 second timer to call this same function again
// but also stores a reference to the timer so that it can be cancelled
lastTimer = setTimeout(startRotation, 3000)
}
// this functions resets the timer and restarts the process
function reset() {
// stop the current timer if there is one
if(lastTimer){
clearTimeout(lastTimer)
}
// restart the process
startRotation()
}
// start the swapping process on start
startRotation()
<input type="button" onclick="reset();">
<img id="picture">
NOT HOW YOU CLEARTIMEOUT:
<html>
<head>
<script>
var i;
function change() {
if(document.getElementById("picture").src == "https://images.pexels.com/photos/248797/pexels-photo-248797.jpeg?auto=compress&cs=tinysrgb&h=350") {
document.getElementById("picture").src = "https://images.pexels.com/photos/67636/rose-blue-flower-rose-blooms-67636.jpeg?auto=compress&cs=tinysrgb&h=350";
}
else {
document.getElementById("picture").src = "https://images.pexels.com/photos/248797/pexels-photo-248797.jpeg?auto=compress&cs=tinysrgb&h=350";
}
i = setTimeout(change, 3000);
}
function fastChange() {
clearTimeout(i);
if(document.getElementById("picture").src == "https://images.pexels.com/photos/248797/pexels-photo-248797.jpeg?auto=compress&cs=tinysrgb&h=350") {
document.getElementById("picture").src = "https://images.pexels.com/photos/67636/rose-blue-flower-rose-blooms-67636.jpeg?auto=compress&cs=tinysrgb&h=350";
}
else {
document.getElementById("picture").src = "https://images.pexels.com/photos/248797/pexels-photo-248797.jpeg?auto=compress&cs=tinysrgb&h=350";
}
i = setTimeout(change, 3000);
}
</script>
</head>
<body onload="setTimeout(change, 3000)">
<input type="button" onclick="fastChange();">
<img src="https://images.pexels.com/photos/248797/pexels-photo-248797.jpeg?auto=compress&cs=tinysrgb&h=350" id="picture">
</body>
</html>
I am building kind of clock and I strongly need to use settimeout().
However, Google Chrome and Safari doesn't allow settimeout() when tab inactive. So, I decided to reloading page when tab active again. (I know, it's not proper way to do it, but I am new at javascript and tried to learn.) I saw this answer and tried to implement to my case. But there is a challenge, I have 3 modals in this page and I don't want reload page when modals are open.
So, I added a global variable equels an integer then changed the value of variable when modals are open.
Here is my code,
var modalCheck = 2;
function openModal() {
var doneModal = document.getElementById("done");
var done = document.getElementsByClassName("closeMessage")[0];
modalCheck = 1;
doneModal.style.display = "block";
done.onclick = function() {
doneModal.style.display = "none";
modalCheck = 2;
}
window.onclick = function(event) {
if (event.target == doneModal) {
doneModal.style.display = "none";
modalCheck = 2;
}
}
}
window.onblur = function() {
window.onfocus= function () {
if (modalCheck = 2) {
console.log(modalCheck);
location.reload(true);
}
}
};
Page reloading is still working, but if modals are opened page reaload immediately.
My question is why this is not working? Is there a syntax error or something like that? What is the solution?
Here's the problem:
if ( modalCheck = 2 ) {
This "if" condition is always true, because you're actually assigning the value "2" to "modalCheck" rather than checking whether "modalCheck" equals "2". The assignment resolves to the value "2", which is treated as a "truthy" expression in your if statement. So this if statement never fails. I recommend
if ( modalCheck === 2 ) {
Others have suggested "if ( modalCheck == 2 ) {", but it's generally better to compare using === rather than == to avoid unexpected weirdness.
i don't know what your html part is, try this code
var modalCheck = 2;
function openModal() {
var doneModal = document.getElementById("done");
var done = document.getElementsByClassName("closeMessage")[0];
modalCheck = 1;
doneModal.style.display = "block";
done.onclick = function() {
doneModal.style.display = "none";
modalCheck = 2;
}
window.onclick = function(event) {
if (event.target == doneModal) {
doneModal.style.display = "none";
modalCheck = 2;
}
}
}
window.onblur = function() {
this.addEventListener('focus',function(){
if (modalCheck == 2) {
console.log(modalCheck);
location.reload(true);
}});
};
I have the following javascript to make the webpage title change again and again after every five seconds.
<script>
var titleArray = ["TITLE-1","TITLE-2","TITLE-3","TITLE-4"];
var N = titleArray.length;
var i = 0;
setInterval(func,5000);
function func(){
if (i == 4) {
i = 0;
}
document.title = titleArray[i];
i++;
}
</script>
I want it to work only when the user has opened a different tab in order to "attract" him/her back to my site.While he/she is on my site I want this javascript to stop working so the title of the webpage is what I simply write in the title tags.
here is a summary of what I want.
<script>
if (the user is not on this tab but has opened and is using a different tab)
{the javascript I have mentioned above};
elce {nothing so the title tags work};
</script>
P.S: Is this a good idea? Got any other suggestions? I just really like thinking out of the box.
Please try with below script.
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script type="text/javascript">
var isActive;
window.onfocus = function () {
isActive = true;
};
window.onblur = function () {
isActive = false;
};
// test
var titleArray = ["TITLE-1","TITLE-2","TITLE-3","TITLE-4"];
var N = titleArray.length;
var i = 0;
function changeTitle(){
if (i == 4) {
i = 0;
}
document.title = titleArray[i];
i++;
}
setInterval(function () {
if(window.isActive !== true){
changeTitle();
}
}, 1000);
</script>
hey, how can I have my download link hidden, and make a count down type thing. Maybe have it count down from 10 and once it's done that have the download link appear, it would be best to do it in js right?
does anyone know how to do this? :D
Thanks
Complete example:
<span id="countdown"></span>
<a id="download_link" href="download.zip" style="display:none;">Download</a>
<noscript>JavaScript needs to be enabled in order to be able to download.</noscript>
<script type="application/javascript">
(function(){
var message = "%d seconds before download link appears";
// seconds before download link becomes visible
var count = 10;
var countdown_element = document.getElementById("countdown");
var download_link = document.getElementById("download_link");
var timer = setInterval(function(){
// if countdown equals 0, the next condition will evaluate to false and the else-construct will be executed
if (count) {
// display text
countdown_element.innerHTML = "You have to wait %d seconds.".replace("%d", count);
// decrease counter
count--;
} else {
// stop timer
clearInterval(timer);
// hide countdown
countdown_element.style.display = "none";
// show download link
download_link.style.display = "";
}
}, 1000);
})();
</script>
You can use setInterval for this. setInterval behaves like a timer, where you can run a certain function periodically. Something like this should do the work(untested):
$(".link").hide();
var iteration = 0;
var timer = setInterval(function() {
if(iteration++ >= 10) {
clearTimeout(timer);
$(".link").show();
$(".counter").hide();
}
$(".counter").text(10 - iteration);
}, 1000);
This will initially hide the download link and run a function every second which counts down from 10. When we reaced ten, we hide the counter and show the link. ClearTimeout is used so that we don't count after we reached ten. Easy as dell.
Edit: As mentioned in the comments, this function is using jQuery to find the elements.
Take a look at the setTimeout function. You can do something like:
function displayLink() {
document.getElementById('link_id').style.display = 'block';
}
setTimeout(displayLink, 10000);
var WAIT_FOR_SECONDS = 10;
var DOWNLOAD_BUTTON_ID = "btnDownload";
if (document.body.addEventListener) {
document.body.addEventListener("load", displayDownloadButton, false);
} else {
document.body.onload = displayDownloadButton;
}
function displayDownloadButton(event) {
setTimeout(function() {
_e(DOWNLOAD_BUTTON_ID).style.display = "";
}, WAIT_FOR_SECONDS*1000);
}
function _e(id) {
return document.getElementById(id);
}