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javascript callback function after several jQuery calls

I got the following code:
$('#some_object_id').hide();
$('div#some_version_div').hide();
$('#some_another_object_id').show();
someFunction();
I want to issue my someFunction() only after the last of these 3 finishes its action. The problem is that from time to time they finish in different order (ie now the last may be the second, the other time the first one etc.) Now someFunction() fires without waiting for these 3 to finish. Any ideas how to fix it? Thank you.

jQuery's hide() and show() functions accept a function as their argument which is called when they finish. (aka, a callback).
$('selector').hide(function onFinish() {
console.log('done')
})
To combine three of them together, I'd convert them to a Promise, like so:
function promisify(func,selector){
return new Promise(function (resolve) {
$(selector)[func](resolve)
})
}
Promise.all([
promisify('hide', '#test'),
promisify('hide', '#test1'),
promisify('show', '#test2')
]).then(function onFinish() {
console.log('done!')
})

You can pass a callback function to hide, and show that gets executed when the animation is complete. So if you want them to execute in order just call each one in the callback of the previous one.
$('#some_object_id,div#some_version_div').hide(()=>{
$('#some_another_object_id').show(()=>{
someFunction();
});
});
And if you want to prevent a bunch of inner callbacks, and not require each animation run dependent of the others, you could use a flag. Increment the flag in each callback, check to see if its at a certain value, and then execute your function if it is.
var flag = 0;
function incrementFlag(){
flag++;
if(flag>=2){
flag=0;
someFunction();
}
}
$('#some_object_id,div#some_version_div').hide(incrementFlag);
$('#some_another_object_id').show(incrementFlag);
You could also modify the above to use a Promise, but will leave that for you to try.

You should use a variable that you initially set to 0 and increase on every complete call. As soon as the variable hit the value 3 and can call your function:
var completed = 0;
elem.hide(400, function(){
completed++;
if(completed > 2) someFunction();
});
//same for other elements...

Javascript synchronous loop, wait until it is finished?

I'm trying to implement this kind of logic in Javascript:
LOOP
doStuff();
END
console.log("Stuff has been done");
I've managed to do it this way:
var loop = function() {
console.log("events");
window.requestAnimationFrame(loop);
}
window.requestAnimationFrame(loop);
console.log("loop is finished");
someOtherCodeGoesHere();
But it doesn't work. Well, it does, but "loop is finished" appears even before RAF is called. This whole code makes sense though, but it's not working as I want it to.
I've also figured out that I can make loop() return a callback function once a condition is met, but I don't want to enclose someOtherCodeGoesHere(); inside it because it's not what I want. Let's say if I have 10 loops, I'd have a callback hell. I just want it to keep going with the code flow, like a plain GOTO if you will.
Any ideas are welcome! :)

I am not familiar with the window.requestAnimationFrame() method, but since you are passing a callback as its only parameter I assume it is an asynchronous function. This means that its invocation does not block the execution of the methods after it. There is no guarantee that the RAF method will call the callback you passed in before the console.log is called. Normally any logic you want to happen after an async method runs you should put in the callback. Dealing with callbacks can be a pain so libraries like async can be a great help. Here is an example of how you might write this using the async lib. (This code is assuming you wanted an infinite loop due to the recursion your attempting in your code)
var loop = function() {
window.requestAnimationFrame(function() {
console.log("events");
});
}
async.forever(loop, function(err) {
console.log(err); // Only gets called if an error occurs
});

Return variable after setTimeout

I'm trying to return a variable only after it has been set within a setTimeout callback. I couldn't think of any other way to do this, but here's my attempt (I know the code seems silly, but it's to work around a Cordova bug). For reasons beyond my understanding, it results in an infinite loop.
function isConnected() {
var done = false;
setTimeout(function() {
done = true;
}, 500);
while (!done) {}
return navigator.connection.type!== Connection.NONE;
}
Can anyone explain to me why this is happening, or provide an alternative?
Update (solution):
function isConnected(callback) {
setTimeout(function() {
callback(navigator.connection.type !== Connection.NONE);
}, 500);
}
isConnected(function(connected) {
if (!connected)
alert('Not Connected');
});

You simply can't solve your problem that way. Because javascript is single threaded, the setTimeout callback can only run when your JS thread of execution finishes so with your infinite loop, it will never get to run and your code will hang. Eventually the browser will complain about a long-running piece of JS and offer to shut it down.
Instead, you need to use a callback function on the setTimeout() and continue your code from that callback. You can't use sequential code for timeouts. You must use asynchronous coding styles.
You could do something like this where you pass in a callback and it calls the callback back and passes it the connected boolean:
function GetConnectedState(callback) {
setTimeout(function() {
callback(navigator.connection.type !== Connection.NONE);
}, 500);
}
Your existing code doesn't seem to offer anything other than a look at the connection state in 1/2 second. With any real sort of asynchronous operation in javascript (such as an ajax call or a websocket connection), there should also be a success or completion callback that will tell you when/if the operation actually completes and you can also trigger the callback based on that (sooner than 1/2 second most of the time). So, this doesn't really look like a complete solution, but it's all you show us you're using.
For example, here's an answer you can look at that calls a callback when an images loads successfully, with an error or times out with no response: Javascript Image Url Verify and How to implement a "function timeout" in Javascript - not just the 'setTimeout'. A similar concept could be used for implementing your own timeout on some other type of asynchronous call.

As I revisit this 5 years later, can't help but to offer up a fancier alternative:
await new Promise(function(resolve) {
setTimeout(resolve, 500);
});
if (navigator.connection.type === Connection.NONE) {
alert('Not Connected');
}

Javascript is single-threaded. The timeout function can't run until your script returns to the main event loop. But as long as you're in the while loop it will never return, so the timeout function never runs, so done is never set to true.
It's not possible in Javascript to wait for an asynchronous event before returning.

How to change css property (like cursor:wait, or background) before AND after ajax calls?

I'm having problems with this code, I'm trying to show a red background while a function is working, and then (only then) I'm changing the background to green.
When the following alert is not commented, I can see the red background for a while and then the green (that's what I want).
But when I comment that alert, seems like the red background is never set and once processData has finished, the background is set to green, correctly.
Can somebody solve this mystery for me? thanks!
function beforeProcess(params){
$('#result').css('background','red');
alert('now i start waiting, while background is red');
$.when(processData(params)).done(
$('#result').css('background','green')
);
}
function process(params){
//This function takes some time, and it makes (indirectly) some synchronous ajax calls (async:false)
}

The view is only updated after the function finishes execution. This can be accomplished using a setTimeout
http://jsfiddle.net/YEVHv/4/
$('#result').css('background', 'red');
//alert('now i start waiting, while background is red');
setTimeout(function () {
$.when(process("")).done(
$('#result').css('background', 'green'));
}, 0);
function process(params) {
for (var i = 0; i < 10000; i++) {
console.log("hello");
}
}
Hope that helps

My guessing is that your function "process" returns quickly... remember that every function call in JS is performed async. If you want to show progress or display some state (red color) while processing, you must be sure that the function process returns after all sub-functions finish. Right now, I can only think about using standard callbacks.
$.when is useful when it used with deferred objects. If the function you use is not a deferred object, the "done" is executed immediately. Please, take a look at the following extract from "http://api.jquery.com/jQuery.when/" : "If a single argument is passed to jQuery.when and it is not a Deferred or a Promise, it will be treated as a resolved Deferred and any doneCallbacks attached will be executed immediately."
Hope this helps

How should I call 3 functions in order to execute them one after the other?

If I need call this functions one after other,
$('#art1').animate({'width':'1000px'},1000);
$('#art2').animate({'width':'1000px'},1000);
$('#art3').animate({'width':'1000px'},1000);
I know in jQuery I could do something like:
$('#art1').animate({'width':'1000px'},1000,'linear',function(){
$('#art2').animate({'width':'1000px'},1000,'linear',function(){
$('#art3').animate({'width':'1000px'},1000);
});
});
But, let's assume that I'm not using jQuery and I want to call:
some_3secs_function(some_value);
some_5secs_function(some_value);
some_8secs_function(some_value);
How I should call this functions in order to execute some_3secs_function, and AFTER that call ends, then execute some_5secs_function and AFTER that call ends, then call some_8secs_function?
UPDATE:
This still not working:
(function(callback){
$('#art1').animate({'width':'1000px'},1000);
callback();
})((function(callback2){
$('#art2').animate({'width':'1000px'},1000);
callback2();
})(function(){
$('#art3').animate({'width':'1000px'},1000);
}));
Three animations start at same time
Where is my mistake?

In Javascript, there are synchronous and asynchronous functions.
Synchronous Functions
Most functions in Javascript are synchronous. If you were to call several synchronous functions in a row
doSomething();
doSomethingElse();
doSomethingUsefulThisTime();
they will execute in order. doSomethingElse will not start until doSomething has completed. doSomethingUsefulThisTime, in turn, will not start until doSomethingElse has completed.
Asynchronous Functions
Asynchronous function, however, will not wait for each other. Let us look at the same code sample we had above, this time assuming that the functions are asynchronous
doSomething();
doSomethingElse();
doSomethingUsefulThisTime();
The functions will be initialized in order, but they will all execute roughly at the same time. You can't consistently predict which one will finish first: the one that happens to take the shortest amount of time to execute will finish first.
But sometimes, you want functions that are asynchronous to execute in order, and sometimes you want functions that are synchronous to execute asynchronously. Fortunately, this is possible with callbacks and timeouts, respectively.
Callbacks
Let's assume that we have three asynchronous functions that we want to execute in order, some_3secs_function, some_5secs_function, and some_8secs_function.
Since functions can be passed as arguments in Javascript, you can pass a function as a callback to execute after the function has completed.
If we create the functions like this
function some_3secs_function(value, callback){
//do stuff
callback();
}
then you can call then in order, like this:
some_3secs_function(some_value, function() {
some_5secs_function(other_value, function() {
some_8secs_function(third_value, function() {
//All three functions have completed, in order.
});
});
});
Timeouts
In Javascript, you can tell a function to execute after a certain timeout (in milliseconds). This can, in effect, make synchronous functions behave asynchronously.
If we have three synchronous functions, we can execute them asynchronously using the setTimeout function.
setTimeout(doSomething, 10);
setTimeout(doSomethingElse, 10);
setTimeout(doSomethingUsefulThisTime, 10);
This is, however, a bit ugly and violates the DRY principle[wikipedia]. We could clean this up a bit by creating a function that accepts an array of functions and a timeout.
function executeAsynchronously(functions, timeout) {
for(var i = 0; i < functions.length; i++) {
setTimeout(functions[i], timeout);
}
}
This can be called like so:
executeAsynchronously(
[doSomething, doSomethingElse, doSomethingUsefulThisTime], 10);
In summary, if you have asynchronous functions that you want to execute syncronously, use callbacks, and if you have synchronous functions that you want to execute asynchronously, use timeouts.

This answer uses promises, a JavaScript feature of the ECMAScript 6 standard. If your target platform does not support promises, polyfill it with PromiseJs.
Look at my answer here Wait till a Function with animations is finished until running another Function if you want to use jQuery animations.
Here is what your code would look like with ES6 Promises and jQuery animations.
Promise.resolve($('#art1').animate({ 'width': '1000px' }, 1000).promise()).then(function(){
return Promise.resolve($('#art2').animate({ 'width': '1000px' }, 1000).promise());
}).then(function(){
return Promise.resolve($('#art3').animate({ 'width': '1000px' }, 1000).promise());
});
Normal methods can also be wrapped in Promises.
new Promise(function(fulfill, reject){
//do something for 5 seconds
fulfill(result);
}).then(function(result){
return new Promise(function(fulfill, reject){
//do something for 5 seconds
fulfill(result);
});
}).then(function(result){
return new Promise(function(fulfill, reject){
//do something for 8 seconds
fulfill(result);
});
}).then(function(result){
//do something with the result
});
The then method is executed as soon as the Promise finished. Normally, the return value of the function passed to then is passed to the next one as result.
But if a Promise is returned, the next then function waits until the Promise finished executing and receives the results of it (the value that is passed to fulfill).

It sounds like you're not fully appreciating the difference between synchronous and asynchronous function execution.
The code you provided in your update immediately executes each of your callback functions, which in turn immediately start an animation. The animations, however, execute asyncronously. It works like this:
Perform a step in the animation
Call setTimeout with a function containing the next animation step and a delay
Some time passes
The callback given to setTimeout executes
Go back to step 1
This continues until the last step in the animation completes. In the meantime, your synchronous functions have long ago completed. In other words, your call to the animate function doesn't really take 3 seconds. The effect is simulated with delays and callbacks.
What you need is a queue. Internally, jQuery queues the animations, only executing your callback once its corresponding animation completes. If your callback then starts another animation, the effect is that they are executed in sequence.
In the simplest case this is equivalent to the following:
window.setTimeout(function() {
alert("!");
// set another timeout once the first completes
window.setTimeout(function() {
alert("!!");
}, 1000);
}, 3000); // longer, but first
Here's a general asynchronous looping function. It will call the given functions in order, waiting for the specified number of seconds between each.
function loop() {
var args = arguments;
if (args.length <= 0)
return;
(function chain(i) {
if (i >= args.length || typeof args[i] !== 'function')
return;
window.setTimeout(function() {
args[i]();
chain(i + 1);
}, 2000);
})(0);
}
Usage:
loop(
function() { alert("sam"); },
function() { alert("sue"); });
You could obviously modify this to take configurable wait times or to immediately execute the first function or to stop executing when a function in the chain returns false or to apply the functions in a specified context or whatever else you might need.

I believe the async library will provide you a very elegant way to do this. While promises and callbacks can get a little hard to juggle with, async can give neat patterns to streamline your thought process. To run functions in serial, you would need to put them in an async waterfall. In async lingo, every function is called a task that takes some arguments and a callback; which is the next function in the sequence. The basic structure would look something like:
async.waterfall([
// A list of functions
function(callback){
// Function no. 1 in sequence
callback(null, arg);
},
function(arg, callback){
// Function no. 2 in sequence
callback(null);
}
],
function(err, results){
// Optional final callback will get results for all prior functions
});
I've just tried to briefly explain the structure here. Read through the waterfall guide for more information, it's pretty well written.

your functions should take a callback function, that gets called when it finishes.
function fone(callback){
...do something...
callback.apply(this,[]);
}
function ftwo(callback){
...do something...
callback.apply(this,[]);
}
then usage would be like:
fone(function(){
ftwo(function(){
..ftwo done...
})
});

Since you tagged it with javascript, I would go with a timer control since your function names are 3, 5, and 8 seconds. So start your timer, 3 seconds in, call the first, 5 seconds in call the second, 8 seconds in call the third, then when it's done, stop the timer.
Normally in Javascript what you have is correct for the functions are running one after another, but since it looks like you're trying to do timed animation, a timer would be your best bet.

asec=1000;
setTimeout('some_3secs_function("somevalue")',asec*3);
setTimeout('some_5secs_function("somevalue")',asec*5);
setTimeout('some_8secs_function("somevalue")',asec*8);
I won't go into a deep discussion of setTimeout here, but:
in this case I've added the code to execute as a string. this is the simplest way to pass a var into your setTimeout-ed function, but purists will complain.
you can also pass a function name without quotes, but no variable can be passed.
your code does not wait for setTimeout to trigger.
This one can be hard to get your head around at first: because of the previous point, if you pass a variable from your calling function, that variable will not exist anymore by the time the timeout triggers - the calling function will have executed and it's vars gone.
I have been known to use anonymous functions to get around all this, but there could well be a better way,

You could also use promises in this way:
some_3secs_function(this.some_value).then(function(){
some_5secs_function(this.some_other_value).then(function(){
some_8secs_function(this.some_other_other_value);
});
});
You would have to make some_value global in order to access it from inside the .then
Alternatively, from the outer function you could return the value the inner function would use, like so:
one(some_value).then(function(return_of_one){
two(return_of_one).then(function(return_of_two){
three(return_of_two);
});
});
ES6 Update
Since async/await is widely available now, this is the way to accomplish the same:
async function run(){
await $('#art1').animate({'width':'1000px'},1000,'linear').promise()
await $('#art2').animate({'width':'1000px'},1000,'linear').promise()
await $('#art3').animate({'width':'1000px'},1000,'linear').promise()
}
Which is basically "promisifying" your functions (if they're not already asynchronous), and then awaiting them

//sample01
(function(_){_[0]()})([
function(){$('#art1').animate({'width':'10px'},100,this[1].bind(this))},
function(){$('#art2').animate({'width':'10px'},100,this[2].bind(this))},
function(){$('#art3').animate({'width':'10px'},100)},
])
//sample02
(function(_){_.next=function(){_[++_.i].apply(_,arguments)},_[_.i=0]()})([
function(){$('#art1').animate({'width':'10px'},100,this.next)},
function(){$('#art2').animate({'width':'10px'},100,this.next)},
function(){$('#art3').animate({'width':'10px'},100)},
]);
//sample03
(function(_){_.next=function(){return _[++_.i].bind(_)},_[_.i=0]()})([
function(){$('#art1').animate({'width':'10px'},100,this.next())},
function(){$('#art2').animate({'width':'10px'},100,this.next())},
function(){$('#art3').animate({'width':'10px'},100)},
]);

I use a 'waitUntil' function based on javascript's setTimeout
/*
funcCond : function to call to check whether a condition is true
readyAction : function to call when the condition was true
checkInterval : interval to poll <optional>
timeout : timeout until the setTimeout should stop polling (not 100% accurate. It was accurate enough for my code, but if you need exact milliseconds, please refrain from using Date <optional>
timeoutfunc : function to call on timeout <optional>
*/
function waitUntil(funcCond, readyAction, checkInterval, timeout, timeoutfunc) {
if (checkInterval == null) {
checkInterval = 100; // checkinterval of 100ms by default
}
var start = +new Date(); // use the + to convert it to a number immediatly
if (timeout == null) {
timeout = Number.POSITIVE_INFINITY; // no timeout by default
}
var checkFunc = function() {
var end = +new Date(); // rough timeout estimations by default
if (end-start > timeout) {
if (timeoutfunc){ // if timeout function was defined
timeoutfunc(); // call timeout function
}
} else {
if(funcCond()) { // if condition was met
readyAction(); // perform ready action function
} else {
setTimeout(checkFunc, checkInterval); // else re-iterate
}
}
};
checkFunc(); // start check function initially
};
This would work perfectly if your functions set a certain condition to true, which you would be able to poll. Plus it comes with timeouts, which offers you alternatives in case your function failed to do something (even within time-range. Think about user feedback!)
eg
doSomething();
waitUntil(function() { return doSomething_value===1;}, doSomethingElse);
waitUntil(function() { return doSomethingElse_value===1;}, doSomethingUseful);
Notes
Date causes rough timeout estimates. For greater precision, switch to functions such as console.time(). Do take note that Date offers greater cross-browser and legacy support. If you don't need exact millisecond measurements; don't bother, or, alternatively, wrap it, and offer console.time() when the browser supports it

If method 1 has to be executed after method 2, 3, 4. The following code snippet can be the solution for this using Deferred object in JavaScript.
function method1(){
var dfd = new $.Deferred();
setTimeout(function(){
console.log("Inside Method - 1");
method2(dfd);
}, 5000);
return dfd.promise();
}
function method2(dfd){
setTimeout(function(){
console.log("Inside Method - 2");
method3(dfd);
}, 3000);
}
function method3(dfd){
setTimeout(function(){
console.log("Inside Method - 3");
dfd.resolve();
}, 3000);
}
function method4(){
console.log("Inside Method - 4");
}
var call = method1();
$.when(call).then(function(cb){
method4();
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>