Develop Reference

How to display spin.js before executing some function?

I want to display a spinner before some complicated function, i.e. dummyCounter(). The code looks like:
function add1() {
msg.html('start counting~<br \>');
document.body.appendChild(div);
spinner.spin(div);
// display spinner before doing stuff
dummyCounter();
}
jsfiddle: http://jsfiddle.net/eGB5t/
However the spinner shows after the dummyCounter() function is finished.
I try to use callback to force spinner display earlier but still no good. Can anybody help? Thanks.
jsfiddle: http://jsfiddle.net/eGB5t/2/

You have a thinking failure. Spinners are usually used for asynchronous tasks, so you can see that there is something in progress. A callback is then used to remove the spin when the async action has finished, since you cannot tell before it starts when it will finish.
I made up a quick example to show you, how such an async function would work in this case, and you can clearly see how the spinner appears slightly before "google finished" appears.
http://jsfiddle.net/eGB5t/4/
I added the following instead of your counting method:
$.ajax("http://google.de").always(function() {
msg.append("google finished");
});
You add the spin before you count, then it counts, then you could remove the spinner. This is perfecty fine. Thing is, if you would count to let's say 9999999999999 (so it would take some seconds), a normal for loop like you're doing is completely blocking the browser, so you won't have any repaints (and therefore no spinner) at all, while the loop is running.
What you would have to do (in this case) is to introduce a worker to have multithreading functionality in javascript.

var x;
function add1() {
msg.html('start counting~<br \>');
spinner.spin(div);
x= setTimeout(document.body.appendChild(div),500);
}

JavaScript unresponsive error on recursive calling of function in for loop

HI I'm iterating control from webpage, i'm getting script unresponsive error if controls are more than 500, though as per my requirement control can grow. I'm using following code.
function callme(val1,val2){
(var i=0;i<1750;i++)
{
var val=some custom function();
var val3=some custom function();
callme(val,val3)
}
}
How to prevent this situation, so that all recursive call should run in asynchronous order.
Kindly suggest.
Thanks in advance.

First of all, having 500 controls in a page is not really a good idea. You might want to look at pagination/splitting based on what your page and code is supposed to be doing.
Async is an option if call me does not return a value and you are not worried about updating the UI immediately. You could set the recursive call to run async by using setTimeout.

jQuery: How can I perform an action after .css has executed?

So my issue is pretty straight forward, since there is seemingly no callback for after a .css is executed, what options do I have for making performing something after a task is done?
I'm creating a simple lightbox, and I need to wait for the center align to finish...
$("#img_lightbox").css("top", top);
So when that completes, I then need to fade in the whole thing, but since there is no callback option (to the best of my knowledge) it will occasionally start fading in before the alignment finishes... how can this prevented?
Any help is appreciated, thank you.

Anything being chained with your jQuery object will execute after the function before it. The easiest way to accomplish what you are asking is with Plugins.
jQuery.fn.myPlugin = function () {
//code to execute
return this;
}
$("#img_lightbox").css("top", top).myPlugin();
You could even write a plugin to execute a custom function, so you do not need to create plugins for every function you might happen to need to run:
jQuery.fn.myCallback= function (callback) {
this.each(function () {
callback.call($(this));
});
return this;
}
$("#img_lightbox").css("top", top).myCallback(function () {
// some code to run where this = $("#img_lightbox")
});
But incase I am still misunderstanding, you may be wanting a callback for your fade function: (otherwise please clarify more)
$("#img_lightbox").fadeIn('slow', function () {
$(this).css("top", top)
});

Adding and removing CSS styles are synchronous functions -- there is no callback because the next statement will be executed once the style has been applied. Rendering of the updated style is slightly different, since that will happen during the next repaint, but unless you're doing some serious number-crunching in your UI code, the difference would be completely unnoticeable. In any case, it would be applied before the 'fading in' starts to happen.
If you're seeing something wrong with your display, I'd suggest that the problem lies elsewhere.

jQuery provides you with a way to tell once the document is "ready" and in the correct state to execute code correctly. Use one of the following:
$(document).ready(function(){
//your code here
});
or the shorter,
$(function(){
//your code here
});
More information at http://api.jquery.com/ready/

Javascript: How do you make function2 execute only after function1 is completely finished?

I have some code, with the order of the functions in the order I want them executed. However, they seem to at the same time (they begin sequentially within microseconds of eachother presumably).
The problem is that some of the functions include animations. How do I make it so the next function doesn't execute until the previous functions are completely finished???
Following is some of my code. I created a callback chain thinking that it would be the solution, but indeed it is not. The functions themselves call jQuery animations. I'm guessing i need to use some type of notofication from jQuery to tell me when animations are done. Anyhow, any advice is greatly appreciated!
show_loader(0, function() {
close_box($target_close, '/', '#' + $target_close.attr('id') + ' .post_wrap', function() {
open_box($target_open, event.value, '.wide-col', function() {
hide_loader(function() {
scroll_to_content($target_open, function() {
});
});
});
});
});
To be precise, I want the scroll_to_content() function to be executed after all the previous actions have been completed in their entirety. Currently, it executes at the same time as everything else, and therefore my page scroll is completely off because the size of my content continues changing after scroll_to_content() is finished.

Callback chains are basically the solution but I suspect you're not threading your callbacks correctly in your calls to jQuery. $.animate(...) has an optional complete callback-- that's where you want to pass the function that should execute after your initial animation finishes. All of the Effects in jQuery UI should have a similar optional argument.
You can use a similar pattern yourself in order to chain event handlers, for instance:
function handler(event, callback) {
// do some work
// ...
callback();
}
This strategy for chaining function evaluations is called continuation-passing style and is handy in a lot of situations. Be careful using it, however, as many people find it more confusing to read than a traditional, sequential implementation.

http://api.jquery.com/queue/
Sorry, I don't have enough time to go into detail, but as the previous commenter said, queues are what you want to be focusing on to solve this problem.

you have 3 options:
1- Split your animations into multiple chained animate() calls.
This is an example to clarify it for you.
2- Follow the answer posted by #dml.
3- Try to use this plugin to add delays between your calls (don't know if it can fix this scenario or not, give it a try)
http://www.evanbyrne.com/article/jquery-delay-plugin

Halt JavaScript execution without locking up the browser

Are you able to halt JavaScript execution without locking up the browser? The way you would normally halt execution is to do an infinite while()-loop, but in the case of FireFox, it locks up the browser until the loop has ended.
What's your take on this?
I am trying to override window.confirm() to implement my own dialog using HTML. I am doing this so I don't have to change existing code (it's a pretty big code-base).
I need to be able to halt execution to allow user-input; to in turn return a boolean like the standard confirm function does:
if (confirm("..."))
{
// user pressed "OK"
}
else
{
// user pressed "Cancel"
}
Update
To my knowledge; this cannot be done using setTimeout() or setInterval() since these functions execute the code thats given to them asynchronously.

confirm() prompt() and alert() are special functions--they call out of the JavaScript sandbox into the browser, and the browser suspends JavaScript execution. You can't do the same thing, since you need to build your functionality into JavaScript.
I don't think there's a great way to drop in a replacement without doing some restructuring along the lines of:
myconfirmfunction(function() {
/* OK callback */
}, function() {
/* cancel callback */
});

Either use callbacks or make your code Firefox-only. In Firefox with support for JavaScript 1.7 and higher, you can use the yield statement to simulate your desired effect. I have created a library for this purpose called async.js. The standard library for async.js includes a confirm method, which can be used as such:
if (yield to.confirm("...")) {
// user pressed OK
} else {
// user pressed Cancel
}

You cannot stop the event thread in JavaScript, so instead you have to work around the problem, usually by using callback functions. These are functions that are run at a later time, but can be passed around like any other object in JavaScript. You might be familiar with them from AJAX programming. So, for example:
doSomeThing();
var result = confirm("some importart question");
doSomeThingElse(result);
Would be converted into:
doSomeThing();
customConfirm("some importart question", function(result){
doSomeThingElse(result);
});
where customConfirm now takes a question and passes the result to the function it takes as an argument. If you implement a DOM dialog with a button, then connect an event listener to the OK and CANCEL buttons, and call the callback function when the user clicks on one of them.

There is an extension to the JavaScript language called StratifiedJS. It runs in every browser, and it allows you to do just that: halting one line of JavaScript code without freezing the browser.
You can enable Stratified JavaScript e.g. by including Oni Apollo ( http://onilabs.com/docs ) in your webpage like:
<script src="http://code.onilabs.com/latest/oni-apollo.js"></script>
<script type="text/sjs"> your StratifiedJS code here </script>
Your code would look like this:
var dom = require("dom");
displayYourHtmlDialog();
waitfor {
dom.waitforEvent("okbutton", "click");
// do something when the user pressed OK
}
or {
dom.waitforEvent("cancelbutton", "click");
}
hideYourHtmlDialog();
// go on with your application

the way you normally halt execution should hardly ever be an infinite while loop.
break up your work into parts, that you call with SetTimeout
change this:
DoSomeWork();
Wait(1000);
var a = DoSomeMoreWork();
Wait(1000);
DoEvenMoreWork(a);
to this:
DoSomeWork();
setTimeout(function() {
var a = DoSomeMoreWork();
setTimeout(function() {
DoEvenMoreWork(a);
}, 1000);
}, 1000);

I don't think there's any way to reasonably re-create the functionality of confirm() or prompt() in your own JavaScript. They're "special" in the sense of being implemented as calls into the native browser library. You can't really do a modal dialog of that sort in JavaScript.
I have seen various UI libraries that simulate the effect by putting an element on top of the page, that looks & acts like a modal dialog, but those are implemented using async callbacks.
You will have to modify the existing library, rather than replacing window.confirm.

I tried using tight looping for this. I needed to slow down a native event (which AFAIK is the only use case for a synchronous wait that can't be re-architected asynchronously). There are lots of example loops out there that claim not to lock up the browser; but none of them worked for me (the browser didn't lock up, but they prevented it from doing the thing I was waiting for in the first place), so I abandoned the idea.
Next I tried this - storing and replaying the event, which seems to be impossible cross-browser too. However depending on the event and how flexible you need to be, you can get close.
In the end I gave up, and feel much better for it; I found a way to make my code work without having to slow down the native event at all.