I am aware that when coding an extension, there is no way we can delay a function call except for using a setTimeout call but here's what I am trying to achieve in a plugin that I am developing for Firefox (this is not for Javascript embedded into a web page by the way):
for (var i = 0; i < t.length ; i++) {
//Load a URL from an array
//On document complete, get some data
}
The idea is simple. I have an array of URLs that I want to parse and extract some data out of. Each of these URLs take some time to load. So, if I try to get some data from the current page without waiting for the page to load, I will get an error. Now, the only way to do this as I know is as follows:
firstfunction: function() {
//Load the first url
setTimeout("secondfunction", 5000);
}
secondfunction: function() {
//Load the second url
setTimeout("thirdfunction", 5000);
}
And so on... I know this is obviously wrong.. I was just wondering how people achieve this in Javascript...
EDIT: Sorry about not being more detailed...
I'm not convinced that this type of foolery is necessary but I'm not an extension dev so who knows. If this is the approach you want, then just have the setTimeout call refer to the same function:
var index;
firstfunction: function() {
// do something with `index` and increment it when you're done
// check again in a few seconds (`index` is persisted between calls to this)
setTimeout("firstfunction", 5000);
}
I am not sure how to do this from a plugin, but what I've done with iframes in the past is attach a callback to the target document's onLoad event.
Maybe something like:
var index = 0;
var urls = [ ..... ];
function ProcessDocument() { ....; LoadNextDocument(); }
function LoadNextDocument() { index++; /* Load urls[index] */; }
document.body.onLoad = ProcessDocument;
Somewhere in there you'd need to test for index > urls.length too for your end condition.
I had same problem but I used recursion instead of looping.
Below is the running code which changes the innerHTML of an element by looping through the list. Hope its helpful.
<Script type="text/javascript">
var l;
var a;
function call2()
{
l = document.getElementById('listhere').innerHTML;
a = l.split(",");
call1(0);
}
function call1(counter)
{
if(a.length > counter)
{
document.getElementById('here').innerHTML = a[counter];
counter++;
setTimeout("call1("+counter+")",2000);
}
}
</Script>
<body onload="call2()">
<span id="listhere">3,5,2,8</span><Br />
<span id="here">here</span>
Related
If I write the html:
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
<h1 id="message">
</h1>
and the JS:
messages = ["Here", "are", "some", "messages."]
$(function() {
for (var i = 0; i < messages.length; i++) {
$('#message').html(messages[i]).delay(1000);
}
});
and load the page, I expect to see each string in the array show up with a delay in between. However, all I see is "messages." appear. It seems that the for loop iterates immediately through each value in the array before performing any delay.
I have seen another method for getting the desired visual result (How can I change text after time using jQuery?), but I would like to know why the earlier method does not work. What is going on when this code is executed?
This is how i would delay my message changing.
function delayLoop(delay, messages) {
var time = 100;
$(messages).each(function(k, $this) {
setTimeout(function()
{
$("#message").html($this);
}, time)
time += delay;
});
}
delayLoop(1000, ["Here", "are", "some", "messages."]);
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="message">
</div>
All I did was for each message delay by an additional delay time.
It works in async mode so its not ui blocking and the messages will display a second after one another.
EDIT:
Removed the .delay from the .html it is redundant.
Note that jQuery's delay is specifically for effects; methods like html do not use the effects queue and are therefore not affected by delay.
This is a problem better solved with JavaScript's native setTimeout function. There are many ways to do this; in fact, you don't even need jQuery!
let messages = ["Here", "are", "some", "messages."];
let delay = 1000;
let header = document.getElementById("message");
messages.forEach(function(message, i) {
setTimeout(function() {
header.innerText = message;
}, delay * i);
});
<h1 id="message" />
You would need something along the lines of
$(function() {
for (var i = 0; i < messages.length) {
var done=false;
$('#message').html(messages[i]).delay(1000).queue(function(){
done=true;
$(this).dequeue();
});
if(done==true){
i++;
}
}
});
Thank you for the answers and comments--very helpful.
I also found this post helpful: Node.js synchronous loop, and from it wrote this (which also works):
function changeText() {
var msg = messages.shift();
$('#message').html(msg).show(0).delay(1000).hide(0, function() {
if (messages.length > 0) {
changeText();
}
});
}
(I used .show and .hide because without them only one of the array values appeared. I'm not sure why that is, but that's a question for another time.)
Hi All i'm developping a game when i run it on chrome it works but when i try it on the emulator i'm getting an error in my javascript code that i can't understand the source or the cause
here's the error:
05-13 11:53:11.726: E/Web Console(790): ReferenceError: Can't find variable: $ at file:///android_asset/www/js/html5games.matchgame6.js:5
the error is in line 5: here's my javascript file content:
var matchingGame = {};
***var uiPlay1 = $("#gamePlay1");*** //////line 5
var uiPlay2 = $("#gamePlay2");
var uiIntro = $("#popup");
var uiExit = $("#gameExit");
var uiNextLevel = $("#gameNextLevel");
var uigameQuit =$("#gameQuit");
var uiPlay3 = $("#gamePlay3");
matchingGame.savingObject = {};
matchingGame.savingObject.deck = [];
matchingGame.savingObject.removedCards = [];
// store the counting elapsed time.
matchingGame.savingObject.currentElapsedTime = 0;
//store the last-elapsed-time
//matchingGame.savingObject.LastElapsedTime = 0;//now
// store the player name
matchingGame.savingObject.palyerName=$("#player-name").html();
matchingGame.savingObject.currentLevel="game6.html";
// all possible values for each card in deck
matchingGame.deck = [
'cardAK', 'cardAK',
'cardAQ', 'cardAQ',
'cardAJ', 'cardAJ',
];
$( function(){init();} );
//initialise game
function init() {
$("#game").addClass("hide");
$("#cards").addClass("hide");
uiPlay1.click(function(e) {
e.preventDefault();
$("#popup").addClass("hide");
startNewGame();
});
uiPlay2.click(function(e) {
e.preventDefault();
$("#popup").addClass("hide");
var savedObject = savedSavingObject();
// location.href =savedObject.currentLevel ;
if (savedObject.currentLevel=="game6.html")
rejouer();
else
location.href =savedObject.currentLevel ;
//ResumeLastGame();
//alert ("level :"+savedObject.currentLevel );
});
uiExit.click(function(e) {e.preventDefault();
//alert("u clicked me ");
}
);
uiPlay3.click(function(e) {
e.preventDefault();
$("#popupHelp").fadeIn(500, function() {
$(this).delay(10000).fadeOut(500)}); });
}
Any idea please thank u in advance
You probably didn't include jQuery.
Presumably you haven't defined the $ function anywhere.
Perhaps you a working from documentation that assumes you have loaded Prototype.js, Mootools, jQuery or one of the many other libraries that set up a variable of that (very poor) name.
make sure you have loaded jquery, mootools, other javascript libraries etc before you use the $.
Have you included your library at the end of your document and you have your script written before the library is downloaded.
make sure you have a script tag that refers to your library and then have your script content.
Also one more thing to note is that your document may not have been loaded when your scriot is executed and some of the controls might not exist on the page, thus make sure you wrap them in an API that will run the function once the document is loaded completely. In jquery you use $(document).ready(function(){});
I am developing a JS app in Ejecta. jQuery was included but the DOM ready doesn't work with Ejecta. Instead on site/app initialization I do something like this:
function func() {
init();
animate();
}
setTimeout(func, 1000);
This gives jQuery time to be loaded and parsed.
I want to display several images of the same size at the same position, one at a time, with a 5s interval between each change. To do so I've used jQuery.Timer, that uses setInterval() to call some show_next_image() function every 5s.
It actually does work with IE, Opera, Safara, Firefox and.. partly with Google Chrome. It's not working with Google Chrome if I open a new window and directly type my website URL: it'll show the second image and stop. And with any other situation (reload, from another link, not right after opening a new window) it'll badly work: one can see the back image before the front image is shown.
Thus I'm wondering whether I've done something wrong with my JavaScript source. What I do is I use a front and a back image. When I want to show the next image, the back img source is set to the new image, and the front image is faded out while the back one is faded in through jQuery. You can check it out at http://www.laurent-carbon.com/ (in French). The two img are identified with bg1 and bg2.
var images = ["/img/IMG_0435bg.jpg", "/img/IMG_0400bg.jpg", "/img/maisonnette 2.jpg", "/img/IMG_0383bg.jpg", "/img/IMG_0409bg.jpg", "/img/IMG_0384bg.jpg"];
var idx = 1;
var waitTime = 5000; // ms
$(document).ready(function() {
$("#bg2").hide();
$.timer(waitTime, load_next);
$.preLoadImages(images);
});
function load_next(timer) {
var toshow = images[idx];
idx++;
idx %= images.length;
back_image().attr('src', toshow);
swap_images();
}
function front_image() {
return (idx % 2 == 0) ? $("#bg1") : $("#bg2");
}
function back_image() {
return (idx % 2 == 0) ? $("#bg2") : $("#bg1");
}
function swap_images() {
back_image().fadeOut('slow');
front_image().fadeIn('slow');
}
Thanks,
Ceylo
Ok I've worked out a solution .... without the use of plugins.
Demo
http://jsfiddle.net/morrison/PvPXM/9/show
source
http://jsfiddle.net/morrison/PvPXM/9/
This approach is a lot cleaner and removes the problem I had while viewing your page in chrome: the animation getting out of sync and flashing.
The only thing you have to do in the HTML is wrap the two images in a <div id="fadeBox" style="position:relative"></div>
$(function() {
var images = [
"http://www.laurent-carbon.com/img/IMG_0435bg.jpg",
"http://www.laurent-carbon.com/img/IMG_0400bg.jpg",
"http://www.laurent-carbon.com/img/maisonnette 2.jpg",
"http://www.laurent-carbon.com/img/IMG_0383bg.jpg",
"http://www.laurent-carbon.com/img/IMG_0409bg.jpg",
"http://www.laurent-carbon.com/img/IMG_0384bg.jpg"
];
var idx = 1;
var max = images.length;
var easing = "swing";
var waitTime = 5000; // ms
var fadeTime = 2000; // ms
var fadeShow = function(fadeTime, fadeDelay) {
var $topImage = $("#fadeBox img:last");
$topImage.fadeTo(fadeDelay, 1, function() {
$topImage.fadeTo(fadeTime, 0, easing, function() {
$topImage
.fadeTo(0, 1)
.insertBefore("#fadeBox img:first")
.attr("src", images[++idx == max ? idx = 0 : idx]);
fadeShow(fadeTime, fadeDelay);
});
});
};
fadeShow(fadeTime, waitTime);
});
Hope this helps
PS thanks to Levi for cleaning the code up a bit.
Answer: http://jsfiddle.net/morrison/RxyZY/
Notes:
You are trying to reinvent the wheel. You are creating a simple slideshow. There are numerous plugins to do exactly this and much more. I used jQuery cycle in my example, which is extremely customizable.
You should wrap your stuff up in a function, creating an expression. In my example, the (function($){}(jQuery)) is what does the trick. It scopes your variables to the function, rather than the global namespace.
Basically I need the thumbnails to rotate every time the user hovers over an image. Here is my failed attempt:
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.6.1/jquery.min.js"></script>
<script type="text/javascript">
$(function() {
$('img').hover(function() {
theImage = $(this).attr('id');
otherImages = $(this).attr('class').split('#');
rotateThumbs(otherImages, theImage);
}, function() {
//
});
});
function rotateThumbs(otherImages, theImage) {
for (i=0; i < otherImages.length; i++) {
setInterval($('#'+theImage).attr('src', otherImages[i]), 1000);
}
}
</script>
<img id="myImage" src="http://www.google.com/images/logos/ps_logo2.png" class="http://www.google.com/images/logos/ps_logo2.png#http://l.yimg.com/a/i/ww/met/yahoo_logo_us_061509.png#http://dogandcat.com/images/cat2.jpg" width="174" height="130" />
Does anyone know how this may be accomplished?
Some issues here.
setInterval requires a function reference as it's first argument, but you are executing code that returns a jQuery object.
setInterval executes the first function repeatedly at the specified interval. Is that what you are trying to do? Swap images every second?
Depending on how you correct the first issue, you could run into an issue where i is otherImages.length and thus the src is set to undefined.
Assuming you worked around issue 3, you will have the problem that the image swaps will happen imperceptibly fast and it will appear as though the last image is always displayed.
Instead, don't use a loop. Increment a counter each time a new image is displayed. Try this:
function rotateThumbs(otherImages, theImage) {
var i = 0;
var interval = setInterval(function() {
$('#'+theImage).attr('src', otherImages[i++]);
if (i >= otherImages.length) {
clearInterval(interval);
}
}, 1000);
}
I've implemented a fully-functional example here. This addresses some of the issues that #gilly3 notes, but uses closures instead of an incrementing counter to keep track of the current image:
$(function() {
$('img').hover(function() {
// declaring these variables here will preserve
// the references in the function called by setInterval
var $img = $(this),
imageList = $img.attr('class').split('#'),
intervalId;
// start the cycle
intervalId = window.setInterval(function() {
var next = imageList.pop();
if (next) {
$img.attr('src', next);
} else {
// stop the cycle
intervalId = window.clearInterval(intervalId);
}
}, 1000);
}, function() {});
});
As you can see, using a closure is much easier when you declare the function passed to setInterval inline, rather than as a separate, named function. You could still have a rotateThumbs function if you wanted, but you might need to do some more work to ensure that the variables were being passed properly.
Edit: I made an updated version that continues to cycle as long as the mouse is hovering.
I have adjusted the answer for Sam, taking pre-loading the image into account, so that you won't have a possible deplay at the first rotation.
function rotateThumbs(otherImages, theImage) {
if(!$('#'+theImage).data('setup')){
$('#'+theImage).data('setup', true); // do not double pre-loading images
var $body = $('body');
for(var j = 0; j < otherImages.length; j++){
$body.append($('<img/>').attr('src', otherImages[j])
.css('display', 'none'));
}
}
var i= 0;
setInterval(function(){
$('#'+theImage).attr('src', otherImages[i++]);
if(i >= otherImages.length){i = 0}
}, 1000);
}
So in my script I have...
<script type="text/javascript">
var images = new Array();
var numImages = 3;
var index = 0;
function setupSwapper() {
for (i = 0; i < numImages; i++) {
images[i] = new Image(266, 217);
images[i].src = "images/image" + i + ".png";
}
setTimeout("swapImage()", 5000);
}
function swapImage() {
if (index >= numImages) {
index = 0;
}
document.getElementById('myImage').src = images[index].src
index++;
setTimeout("swapImage()", 5000);
}
</script>
And then I have <body onload="setupSwapper()"> to setup the body.
and <img width=266 height=217 id="myImage" name="myImage" src="images/image0.png"></img> elsewhere in my document.
Only the initial image (image0.png) is showing up. I'm probably blind from having looked at this so long. The images are not swapping.
Use FireBug or a similar tool for debugging what's going on:
Does the img DOM element in fact gets its src changed ?
Do you see any network activity trying to load the images ? does it succeed ?
Set up breakpoints in your code and see what happens in the debugger
BTW - You can use setInterval instead of setTimeout - it sets a repeating timer
You're missing the () in the definition of "setupSwapper".
Also it's setTimeout, not setTimeOut.
Finally, get rid of the "type" attribute on your <script> tag.
You might want to start "index" at 1 instead of 0.
The way to go:
setTimeout(swapImage, 5000);
[FORGET] the type attribute has nothing to do with it
[FORGET] the index has nothing to do with it
[OPTIONAL] remove "name" attribute from the image (useless)
[OPTIONAL] close image tags like <img />
Note: 2-5 is about correctness. Only the first one is important to get it work.
Get Firebug, use it's debugger to put breakpoints inside swapImage to see if it is hit after the timeout. Another way is to use the console.* apis to see what's happening(e.g. console.log).