I am new to Javascript and would like to know if the following function should create a transition scrolling down to a set scroll position and if not, what am I misunderstanding about the time out or scroll to methods..
function scrollDownToMovie() {
for (var scrollbit = 10; scrollbit < 900; scrollbit += 10) {
window.setTimeout(function({window.scrollTo(0,scrollbit);}
,scrollbit*100);
}
}
Thank you
Try this. It's not perfect but it should do what you want.
var scrollbit=10;
function scrollDownToMovie() {
var time=setTimeout(function(){scrollDownToMovie();},50); //fifty can be whatever increment you want.
window.scrollTo(0,scrollbit);scrollbit+=10;
if(scrollbit>890){clearTimeout(time);}
}
Related
I'm trying to build a simple image slider (but using a fade effect). Every two seconds, the image should change to another image. At the end, it should call repeat_sponsor() again, to start over, so it becomes a loop.
I've written this (highly ineffective) code for 5 images. Turns out I'm going to need it for around 50 images. My editor just freezes when I add too much code.
I've tried using while-loops, but I just can't figure it out how to do this the right way.
Anyone who can help me with this?
function repeat_sponsor()
{
$("#sponsor2").hide();
$("#sponsor3").hide();
$("#sponsor4").hide();
$("#sponsor5").fadeOut("slow");
$("#sponsor1").fadeIn("slow", function() {
setTimeout(function(){$("#sponsor2").fadeIn("slow", function() {
setTimeout(function(){$("#sponsor3").fadeIn("slow", function() {
setTimeout(function(){$("#sponsor4").fadeIn("slow", function() {
setTimeout(function(){$("#sponsor5").fadeIn("slow", ...
(function (){
var cnt = 50; //set to the last one...
var max=50;
function show() {
$("#sponsor" + cnt).fadeOut("slow"); //if you want the fadeout to be done before showing next, put the following code in the complete callback
cnt++;
if(cnt>max) {
cnt=1;
}
$("#sponsor" + cnt).fadeIn("slow");
window.setTimeout(show, 2000);
}
show();
})();
But the real issue is the fact you are loading tons of images from the start. You will be better off changing it so you only have a small subset of images and change the source.
You should use some sort of for loop and a class for hiding the images. and add a max value that if checks out resets c & i
var i=0;
var c=1;
function repeat_sponsor()
{
$("#sponsor"+i).fadeOut("slow");
$(".sponsers").hide()
$("#sponsor"+c).fadeIn("slow", function() {
window.setTimeout(repeat_sponsor(), 3000);
}
i++;
c++;
}
Just run a function every two seconds with setInterval and appropriately target your different sponsor divs:
var i = 1;
var max = 50;
setInterval(function() {
// Could target all other sponsor images with a class "sponsor"
$('.sponsor').fadeOut();
// Execute code on the target
$("#sponsor" + i).fadeIn();
if (i === max) {
i = 0;
}
i++;
}, 2000);
I'm trying to make a auto-scrolling div that go to its top when it reaches the end. But it doesn't work...
function scrollPannel()
{
var pannel = document.getElementById('pannel');
if (typeof scrollPannel.count == 'undefined')
{
scrollPannel.count = 0;
}
else
{
scrollPannel.count += 2;
}
// trouble is here
if ((scrollPannel.count - pannel.scrollHeight) > pannel.clientHeight)
{
scrollPannel.count = 0;
}
pannel.scrollTop = scrollPannel.count;
setTimeout('scrollPannel()', 500);
}
HTML:
<div id='pannel' style="height:200px;overflow:auto" onmouseover="sleepScroll()">
<p>...</p><!-- long text -->
</div>
And after, I will need to find how to stop scrolling when "onmouseover" occures.
EDIT: I did not explained the problem clearly. In fact, I have tried something like:
if (scrollPannel.count > pannel.scrollHeight)
{
scrollPannel.count = 0;
}
The problem is that scrollHeight seems greater than div inner text. So it makes a lot of time to return to the top.
So I need an element property of which I could use the value to compare with my count variable. However I don't know Javascript a lot and I could not find anything. I hope it is as well simple as I think of it.
Try:
// calculate max scroll top position (go back to top once reached)
var maxScrollPosition = element.scrollHeight - element.clientHeight;
// example
element.scrollTop = maxScrollPosition;
That should do what you need.
You could try using the scrollHeight property.
https://developer.mozilla.org/en-US/docs/Web/API/element.scrollHeight
The solution I have involves jQuery, hope that's not a problem.
JavaScript:
var timeout;
function scrollPannel()
{
var divHeight = $("#pannel").height() / 2;
var scrollCount = $("#pannel").scrollTop();
var scrollHeight = $("#inside").height() - 20 - divHeight;
scrollCount += 2;
if ((scrollCount - scrollHeight) > 0)
{
scrollCount = 0;
}
$("#pannel").scrollTop(scrollCount);
timeout = window.setTimeout(scrollPannel(), 100);
}
function scrollStop() {
window.clearTimeout(timeout);
}
HTML:
<div id='pannel' onmouseover="scrollStop();" onmouseout="scrollPannel();">
<p id="inside"></p><!-- long text -->
</div>
Explanation:
jQuery's .height() of the inside element <p> gives us the actual height you're looking for, but it's not enough for reaching the bottom, since that happens before we reach the element's height. A little investigation shows that the "top" of scrollTop() is about half way inside the original div's height. You may need to play around with divHeight to get the exact results you're looking for.
Of course, I also included a method for stopping and continuing scrolling.
Good luck!
You should use scrollHeight property but to call it, you need to use an index like that:
$('#pannel')[0].scrollHeight;
If you set the scrollTop and scrollLeft to really high silly values they only ever get set as their maximum allowed values which I think is what you need? You can then use them to work out the scroll center if you wished.
See snippet example.
var mB = document.getElementById('myBox');
var mR = document.getElementById('myResult');
// Set the top and the left to silly values
mB.scrollTop = 99999999;
mB.scrollLeft = 99999999;
// They will only end up being set as their max
mR.innerHTML = "maxTop="+mB.scrollTop+"<br>maxLeft="+mB.scrollLeft;
// Now take the max values and divide by 2 to scroll back to middle.
mB.scrollTop = mB.scrollTop/2;
mB.scrollLeft = mB.scrollLeft/2;
#myBox{
overflow:auto;
}
#myContent{
border:1px solid black;
background-color:red;
}
<div id='myBox' style='width:300px;height:300px'>
<div id='myContent' style='width:500px;height:800px;line-height:800px;'><center>I am the center of the content</center></div>
</div>
<div id='myResult'></div>
I have got one solution....
function findMaxReach(){
let maxReach =0
document.querySelector('.YourElement').scrollLeft = 100000;
maxReach = document.querySelector('.YourElement').scrollLeft;
document.querySelector('.YourElement').scrollLeft = 0;
return maxReach
}
So I've created the following function to fade elements in and passed in a div that I want to fade in which in this case is an image gallery popup that I want to show when a user clicks an image thumbnail on my site. I'm also passing in a speed value (iSpeed) which the timeout uses for it's time value. In this case I'm using 25 (25ms).
I've stepped through this function whilst doing so it appears to be functioning as expected. If the current opacity is less than 1, then it is incremented and it will recall itself after the timeout until the opacity reaches 1. When it reaches one it stops fading and returns.
So after stepping through it, I take off my breakpoints and try to see it in action but for some reason my gallery instantly appears without any sense of fading.
var Effects = new function () {
this.Fading = false;
this.FadeIn = function (oElement, iSpeed) {
//set opacity to zero if we haven't started fading yet.
if (this.Fading == false) {
oElement.style.opacity = 0;
}
//if we've reached or passed max opacity, stop fading
if (oElement.style.opacity >= 1) {
oElement.style.opacity = 1;
this.Fading = false;
return;
}
//otherwise, fade
else {
this.Fading = true;
var iCurrentOpacity = parseFloat(oElement.style.opacity);
oElement.style.opacity = iCurrentOpacity + 0.1;
setTimeout(Effects.FadeIn(oElement, iSpeed), iSpeed);
}
}
}
Here's where I'm setting up the gallery.
this.Show = function (sPage, iImagesToDisplay, oSelectedImage) {
//create and show overlay
var oOverlay = document.createElement('div');
oOverlay.id = 'divOverlay';
document.body.appendChild(oOverlay);
//create and show gallery box
var oGallery = document.createElement('div');
oGallery.id = 'divGallery';
oGallery.style.opacity = 0;
document.body.appendChild(oGallery);
//set position of gallery box
oGallery.style.top = (window.innerHeight / 2) - (oGallery.clientHeight / 2) + 'px';
oGallery.style.left = (window.innerWidth / 2) - (oGallery.clientWidth / 2) + 'px';
//call content function
ImageGallery.CreateContent(oGallery, sPage, iImagesToDisplay, oSelectedImage);
//fade in gallery
Effects.FadeIn(oGallery, 25);
}
Could anyone help me out?
Also, I'm using IE10 and I've also tried Chrome, same result.
Thanks,
Andy
This line:
setTimeout(Effects.FadeIn(oElement, iSpeed), iSpeed);
calls Effects.FadeIn with the given arguments, and feeds its return value into setTimeout. This is exactly like foo(bar()), which calls bar immediately, and then feeds its return value into foo.
Since your FadeIn function doesn't return a function, that would be the problem.
Perhaps you meant:
setTimeout(function() {
Effects.FadeIn(oElement, iSpeed);
}, iSpeed);
...although you'd be better off creating that function once and reusing it.
For instance, I think this does what you're looking for, but without recreating functions on each loop:
var Effects = new function () {
this.FadeIn = function (oElement, iSpeed) {
var fading = false;
var timer = setInterval(function() {
//set opacity to zero if we haven't started fading yet.
if (fading == false) { // Consider `if (!this.Fading)`
oElement.style.opacity = 0;
}
//if we've reached or passed max opacity, stop fading
if (oElement.style.opacity >= 1) {
oElement.style.opacity = 1;
clearInterval(timer);
}
//otherwise, fade
else {
fading = true;
var iCurrentOpacity = parseFloat(oElement.style.opacity);
oElement.style.opacity = iCurrentOpacity + 0.1;
}
}, iSpeed);
};
};
Your code has a lot of problems. The one culpable for the element appearing immediately is that you call setTimeout not with a function but with the result of a function, because Effects.FadeIn will be executed immediately.
setTimeout(function(){Effects.FadeIn(oElement, iSpeed)}, iSpeed);
will probably act as you intend.
But seriously, you probably should not re-invent this wheel. jQuery will allow you to fade elements in and out easily and CSS transitions allow you to achieve element fading with as much as adding or removing a CSS class.
T.J. and MoMolog are both right about the bug: you're invoking the Effects.FadeIn function immediately before passing the result to setTimeout—which means that Effects.FadeIn calls itself synchronously again and again until the condition oElement.style.opacity >= 1 is reached.
As you may or may not know, many UI updates that all take place within one turn of the event loop will be batched together on the next repaint (or something like that) so you won't see any sort of transition.
This jsFiddle includes the suggested JS solution, as well as an alternate approach that I think you may find to be better: simply adding a CSS class with the transition property. This will result in a smoother animation. Note that if you go this route, though, you may need to also include some vendor prefixes.
I have a jsfiddle for this
Jsfiddle
The problem is, I am trying to create a script that ones a button is clicked flashes an image (car lights) on and off for a period of time. It works fine, but in IE8 since the lights are png the animation for it is causing a black background and border as it blinks on and off. So I trying to duplicate the same thing, but without using animation.
In my jsfiddle, the first function for the first click div represents what i am trying to do without animation, but it is not repeating. The code:
$('.oneD').click(function(){
for (var i = 0; i <= 9; i++) {
$('.oneP').show();
setTimeout(function(){
$('.oneP').hide();
}, 1000);
}
});
The 2nd function is the one I already created that does work, but it has the animation:
$('.twoD').click(function(){
for (var i = 0; i <= 9; i++) {
$(".twoP").fadeIn(1000, function () {
$(".twoP").hide();
});
}
});
Keep in mind that the jsfiddle is just a simple mock not using images. I am just looking for the functionality in which i can incorporate this. I appreciate your time in helping me with this.
instead of setTimeout() use setInterval() and clearInterval() like this:
$('.oneD').click(function(){
$('.oneP').show();
var interval = setInterval(function(){
$('.oneP').hide();
}, 1000);
//*after a number of time or loop
interval.clearInterval();
});
setInterval() "Loop" throught the function it is given every number of millisecond you pass it. and clearInterval() stop the "Loop".
I'd do it like this :
$('.oneD, .twoD').on('click', function(){
for (var i=0; i<9; i++)
$('.'+this.className.replace('D', 'P')).delay(1000).show(0)
.delay(1000).hide(0);
});
FIDDLE
This uses a selector for both elements and the same event handler, then swaps out the D for a P in the showing and hiding.
As for using delay() and making this work, hide() and show() will work just as the animated jQuery methods if a value for the duration is passed, even if that value is zero.
Fiddle here: http://jsfiddle.net/HxFpr/
var i;
$('.twoD').click(function(){
i = 0;
loopFlash();
});
function loopFlash(){
if(i < 10){ // flash 5 times (1 on 1 off = 2 cycles)
$('.twoP').toggle();
var flashing = setTimeout(loopFlash,500);
}
i++;
}
Yet another solution for you.
No Animation - with single interval
With animation - pure jQuery
http://jsfiddle.net/x6Kpv/6/
var noAnimationHandler = function() {
setInterval(function() {
var $el = $('.oneP');
$el[$el.is(":visible") ? "hide" : "show"]();
}, 800);
};
var animationHanddler = function() {
$('.twoP').fadeIn(300, function() {
$(this).delay(150).fadeOut(300, animationHanddler);
});
}
$('.oneD').click(noAnimationHandler);
$('.twoD').click(animationHanddler);
Thanks
I am designing a website where the background sits in a div that has a negative z-index with position:fixed. I then have section divs that scroll over it. My goal is to change the background image when each section's top position is passed by the scrollTop function. My jQuery code currently creates an array of each sections top position using:
var secTops = [];
$('section').each(function(i) {
var t = $(this).offset();
secTops.push(t.top);
});
I then thought I would create a variable upon scroll() that was the scrollTop() position like so:
$(window).scroll(function() {
var winTop = $(this).scrollTop();
});
But here is where I am stuck. The best I can come up with (which doesn't work right) is this:
for (i = 0; i < $('section').length; i++) {
var pos = secTops[i];
if (winTop < pos) {
$('#background').css('background', bgFront + (i+1) + bgBack);
} else {
$('#background').css('background', bgFront + (i+2) + bgBack);
};
};
But this isn't right. You can disregard the second half of my .css() function. I've created variables and labeled my images appropriately, so i know that works. Right now, the for loop runs through the entire iteration and is stuck at the full section.length and thus only flips between 2 background images. I need this to constantly check my winTop variable against the top positions of my sections and change the background accordingly. I could do this with a lot of if/then, or maybe even a lengthy switch, but there has to be a cleaner way to do this. Can anyone help me out here?
Here's a JSFiddle that uses colors instead of images but shows the same problems. http://jsfiddle.net/kyleshevlin/5N5WU/1/
this has no chance to work. you need to change it to something like this (this is kinda pseudocode, just to give you a picture:
sections = [];
$(document).ready(function() {
$('section').each(function() {
sections.push($(this))
});
})
$(window).scroll(function() {
var s = $(window).scrolTop();
var currentIndex;
for ( var i = 0; i < sections.length; i++) {
if (( s > sections[i].offset().top) && ( s <= sections[i+1].offset().top)) {
currentIndex = i;
}
}
$('#background').css('background', bgFront + (i+1) + bgBack);
})