How can I profile setTimeout functions existance in JS - javascript

I am having a problem understanding which function runs (probably in infinite loop) in my JS code.
Is there a plug\way to see the list of the setTimeout functions that are running?

All you have to do is hook into your setTimeout function and log stuff:
var _temp = setTimeout;
setTimeout = function() {
_temp.apply(this, arguments);
alert(arguments[0]);
};
Put that snippet at the top of your code. Every time anything invokes setTimeout, you'll see exactly who's doing it.
Also, instead of alert, use console.log or something similar.

You can probably use the Firebug Firefox extension to put a breakpoint in. http://getfirebug.com/

Related

window.onload not working after page load chrome dev console

window.onload doesn't seem to run the specified function in the chrome console and I can't seem to find anyone with the solution.
Code:
function preStart() {
console.log("Hello");
}
window.location = 'https://www.google.com/';
window.onload = preStart;
When ran the window.location successfully runs but "preStart" does not.
I realize that window.onload doesn't work after window.location but is there a solution to this? (Where the function runs after the page loads)
Since I am relatively new to JavaScript please explain any answers/solutions.
Any help with this would me much appreciated.
You basicly are passing the preStart function to the window.onload method.
I see a bit misunderstanding in beginner javascript developers with the difference between preStart and preStart() functions.
in some cases like this:
SetTimeout(function(){
}, 2000)
you can pass directly a function to the SetTimeout, like you did above, so if your preStart has some logic that you want to execute after 2000 seconds you could:
SetTimeout(preStart,2000)
you can see that the function preStart was passed directly without '()' it doesn't need to be called since the SetTimeout expect the function.
in your case you want to execute the preStart on windows.load, so ou need the '()' to execute it.
So do something like this:
function preStart() {
console.log("Hello");
}
window.location = 'https://www.google.com/';
window.onload = preStart();
Sorry if i i did a curve to explain the question, but i hope it helped.

long run error after calling the javascript method from the action script

I am trying to call a method of a javascript from the actionscript using the ExternalInterface.
Here is the code in action script
private function onKickEvent(e:LogoutEvent):void{
ExternalInterface.call("LoginFound","message");
return;
}
And this is my javascript mwthod
function LoginFound(message){
alert(message);
anotherInstanceExists=true;
}
Everything is working fine, but the only thing is when act on the alert box which is shown in the javascript after some 20 secs, the exception is thrown from the flash player that a script has been running longer than expected time 15 sec.
How can i avoid this?
Best way to fix this issue is to add setTimeout inside your javascript on the alert line.
It should look like this:
setTimeout(function(){ alert(message) }, 1);
By doing it this way execution won't stop because of the alert.
When you call js function from the actionscript, that function have to work and return value not longer than in 15 sec. Javascript works in single thread,and when you call LoginFound function, alert stops farther executions on the thread.
function LoginFound(message){
alert('something');
//Nothing will be executed unless `alert` window will be closed
}
However you can handle such situation (the execution,which is longer than 15 sec) in Actionsript by using try/catch:
private function onKickEvent(e:LogoutEvent):void{
try{
ExternalInterface.call("LoginFound","message");
}catch(e:Error){
//Do something
}
}
I think your onKickEvent is called frequently
so that the javascript is called regularly. finally the browser timeout event
occurs. It always happen in recursive function.

Javascript setInterval runs only one time

setInterval(this.Animate(), this.speed);
This is expected to be run every this.speed times. Yes, but the browsers run it only one time. What are the possible reasons for that?
Try to run your function without the parentheses, when you put parentheses it always calls the function instead of passing it, which is what you want here:
setInterval(this.Animate, this.speed);
If it still doesn't work, you should debug and find out what is the scope for 'this', as 'this' might change. You can do that by adding a breakpoint in your browser's JS debugger.
Also, you can try this to avoid the scope problem with 'apply'
var animate = this.animate.apply(this)
setInterval(animate, this.speed);
p.s: It might be a good choice to avoid setInterval for animation as they might queue and then fire at once. Instead call setTimedout once and again at the end of the function (this.Animate) as so to create a loop.
If Animate is a derived function from the prototype, you'll have to use:
setInterval(this.Animate.bind(this), this.speed);
Do the following:
setInterval(this.Animate, this.speed);
You are executing the function instead of assigning a reference to the function to be executed at a certain interval...
Let us look at your code
setInterval(this.Animate(), this.speed);
What it is saying is run the function this.Animate() right away and store what ever it returns to be called.
What you want to do is create a closure
var that = this;
setInterval( function(){ that.Animate() }, this.speed);
The that maintains the current scope.
If you're looking for a JQuery refresh script, try:
refreshId = setInterval(function() {
// Events or Actions
}, 5000);
If you ever want to Pause or Stop this, use clear interval: clearInterval(refreshId);.

How do I stop Javascript execution? And all timers? (How to stop a function from polling - or monkeypatching it)

I want to stop a script from executing, similar to what the Esc key does in Firefox. It stops all Javascript from running on that page as well as all gif animations.
Is there a function I could call which would stop everything?
Depending on how the offending module is organized, perhaps you can monkey-patch it without having to change its source code.
For example, if the annoying polling function is global or namespaced you can try to replace it with a useless stub:
//save the old version of the function, in case
//we need to restore it afterwards
var nasty_function = His.Namespaced.Evil.func;
//put our own stub in place
His.Namespaced.Evil.func = function(what, args, it , should, receive){
return somthing_that_signals_a_failed_poll;
}
No, there is nothing like that. And there's also no real reason for it: you write the code, you can make it stop doing things if you want to.
Plus: if there were such a function that stopped all JS activity... how would you make it start up again?

Why windows.onload is executed several times?

I'm binding the window.onload event like this
// It's a little more complex than this, I analyze if there is any other function
// attached but for the sake of the question it's ok, this behaves the same.
window.onload = myfunction;
Onload is triggered twice on my local machine a several times on the production server
If I change it by the jQuery equivalent
$jQuery(window).load(myfunction);
It behaves as expected (executed only once).
Could you help me to understand possible reasons why the first option it's not working as supposed?
Thanks!
The parentheses on your assignment — myfunction() — executes your function. You haven't shown what myfunction does, but this means that the return value from that function is being assigned to window.onload, not the function itself. So, I don't know how that is getting executed, unless you have somehow got that to work, like ending the function with return this;
You want
window.onload = myfunction;
Given the nature of window.onload, it seems unlikely that pure browser events alone are making both calls to myfunction. Therefore, a breakpoint inside your function will help you see the call stack. I've included screenshots for Chrome.
Sample code:
var alertme = function() {
alert("Hello");
}
window.onload = alertme;
function testsecondcall() {
alertme();
}
testsecondcall();
Open your page in Chrome.
After the page has loaded once, open the Developer Tools panel and put a breakpoint on the line inside your function, then refresh the page.
Check the call stack of both times that it breaks. One will be empty (the actual window.onload). The other should give you some information like the following:
On the right, under "Call Stack", you see alertme is called by testsecondcall

Categories

Resources