I need this because I often work on existing projects, and I'm required to crash right into the middle of somebody else's work. With little time nowadays, I'm looking for whatever tool I can find to do this:
Load a JS application
Start / Pause recording activity
Show me exactly what happened, in the form of what functions were called without requiring me to change the source code.
For example:
<script language="javascript">
var fn1 = function(strvar){ alert('var='+strvar); fn2(strvar); }
var fn2 = function(strvar2){ alert('var='+strvar2); }
</script>
click here
After I click the anchor, (at best) should get something like this:
(click) event on a
(call) fn1("click here")
(call) fn2("click here") from inside fn1 called at pct. 2
Some sort of stack tracing but without having to alter the source because it takes formidable time as it is.
If you write
debugger;
in your innermost function, you can open firebug or the chrome dev tools and their debugger will pause when it hits that line. Then in the section on the right of the tools, you can see the stack trace and other relevant data (locals, etc...).
You only need to add one line to a function you own and it will show you any calls made with anyone's code.
Related
I'm trying to debug something live on a customer website and my code is all inside an anonymous function block. I don't know if there's anyway to reach that code to execute functions or look at variables in there. I can't put a breakpoint either because this code is dynamically generated each time the page is refreshed and the breakpoint doesn't stick.
(function() {
var Date = "14 September 2022 14:44:55"; // different every refresh for example
var Holder = {
var Items = {
item1: "Value1",
item2: "Value2"
};
function getItem(name) {
return Items[name];
};
function setItem(name, value) {
Items[name] = value;
};
setTimeout(DoSomething(), 2000);
})();
That's not the actual code, just a bare minimum example to illustrate the problem.
Is there anyway to get reach getItem() or Items?
Without a breakpoint that code probably runs to completion then POOF it's all gone anyway.
Redefine setTimeout
If it really is the case that the code inside the anonymous function calls other browser methods, you might be able to insert a detour at runtime that you can then put a breakpoint on.
For this to work, you will need to be able to inject new code into the page before the anonymous code, because there's no other way to invoke the IIFE.
Your example code uses setTimeout, so here's what I would try to insert:
let realSetTimeout = window.setTimeout
window.setTimeout = (...args) => {
debugger
return realSetTimeout(...args)
}
Lots of unrelated code might be calling setTimeout, in which case this could break the page or just make debugging really tedious. In that case, you might make it only debug if one of the setTimeout args has a value that's used in your example, e.g.:
// only break for our timeout
if(args[1] === 2000) debugger
Something like that might not trigger for only your code, but it would hugely reduce the number of other codepaths that get interrupted on their journey through the commonly-used browser capability.
Alternatively, use Charles Proxy to rewrite the body of the HTML page before it enters your browser. You could manually insert a debugger call directly into the anonymous function. Charles is not free, but I think they have a demo that might let you do this. If you do this professionally, it's probably a good purchase anyway. Your employer might even pay for the license.
If you can't use Charles (or a similar tool), you could instead set up a local proxy server using Node which does the rewrite for you. Something like that might only take an hour to throw together. But that is a bigger task, and deserves its own question if you need help with that.
No unfortunately.
The variables inside of the anonymous object are created in a scope which is inaccessible from the outside.
One of the main benefits of using a closure!
You’ll have to find a way to insert your own code inside of it by modifying the function that is generating those objects. If you can’t do that, then you’ll have to take the fork in the road and find another way.
So I have such a weird question and I don't know if this is possible, but I will give it a shot anyways.
We have implemented OneTrust, which is a third-party cookie consent vendor and it works great and all, but we have one small hiccup that we are trying to resolve.
So within the below function:
toggleVideo: function (videoWrapper, src, cover, type, element) {
var videoElement = video.buildVideo(src, type);
// We build out video-player element
videoWrapper.html(videoElement);
// We define our variables
let onetrust = window.OneTrust;
let onetrust_obj = window.ONETRUST_MODULE;
let target = videoWrapper.html(videoElement).children('iframe');
console.log(onetrust.Close());
// Now we wait and observe for a src attribute and then show the video.
onetrust_obj.src_observer(target, function() {
video.toggle_show(videoWrapper, cover);
});
},
We have an <iframe> element that when clicked play, will wait for consent to execute - The problem is that it needs to "refresh" OneTrust so that it can change the data-src to src attribute (This is all handled using OneTrust JS, so I have no control).
When I add in the console.log(onetrust.Close());, it works just as intended and resumes playing the video when consent is given, the downfall is that it outputs an error in the console. If I remove it, the videos will not play after consent is given.
I don't want to actually execute the onetrust.Close() method as it will close the banner.
OneTrust doesn't have a proper way to "Refresh" their initialization, the techs told me that this was a one-off case, where they don't even know how to handle it.
My questions:
Is there a way that I can properly call onetrust.Close() (Seems to be the only call that actually engages the video to play after) without actually executing it?
If not, is there a way that I can somehow similarly log it, but not actually log it in the console?
Thanks all!
Strange one, may be a race-condition issue so making your code run in the next procedural iteration may resolve the issue - this can be done by adding a setTimeout with no timer value.
setTimeout(() => {
onetrust_obj.src_observer(target, function() {
video.toggle_show(videoWrapper, cover);
});
});
Alternatively, it may be worth digging into the onetrust.Close() method to see if there are any public utilities that may help 'refresh' the context you are working in.
Another idea would be to see what happens after if you ran the onetrust_obj.src_observer code block again.
EDIT: I would like to be clear that I'm just trying to help resolve debugging this, without seeing a working environment it's difficult to offer suggestions 😄
I am trying to implement the displaying of a web page in Qt. I chose to use the Qt WebEngine to achieve my task. Here's what I did :
Wrote a sample web page consisting of a empty form.
Wrote a JS file with just an API to create a radio button inside the form.
In my code, it looks like this :
View = new QWebEngineView(this);
// read the js file using qfile
file.open("path to jsFile");
myJsApi = file.Readall();
View->page()->runjavascript (myjsapi);
View->page()->runjavascript ("createRadioButton(\"button1\");");
I find that the runJavaScript() function has no effect on the web page. I can see the web page in the output window, but the radio button I expected is not present. What am I doing wrong?
I think you will have to connect the signal loadFinished(bool) of your page() to a slot, then execute runJavaScript() in this slot.
void yourClass::mainFunction()
{
View = new QWebEngineView(this);
connect( View->page(), SIGNAL(loadFinished(bool)), this, SLOT(slotForRunJS(bool)));
}
void yourClass::slotForRunJS(bool ok)
{
// read the js file using qfile
file.open("path to jsFile");
myJsApi = file.Readall();
View->page()->runJavaScript(myjsapi);
View->page()->runJavaScript("createRadioButton(\"button1\");");
}
I had this problem, runJavascript didn't have any effect. I had to put some html content into the view (with page().setHtml("") before running it.
Check the application output, it might contain JavaScript errors. Even if your JS code is valid, you might encounter the situation where the script is run before DOMContentLoaded event, that is document.readyState == 'loading'. Therefore, the DOM might not be available yet, as well as variables or functions provided by other scripts. If you depend on them for your code to run, when you detect this readyState, either wait for the event or try calling the function later, after a timeout. The second approach with timeout might be needed if you need to get the result of the code execution, as this can be done only synchronously.
I am trying to debug legacy scripts with Firebug. As per my knowledge (Which I got yesterday)
we use Step over (F10) to debug line by line and Step into (F11) to dig into JS function.
But when I use Step into on any JS function call, it takes control to next line. I want to see what is hidden inside the function. How can we do it ?
I kept break-point inside the function and then tried Step into then it takes control inside the function body. But it is tedious to find each function method and set break-point.
Is there any other way to do it ? or which is the right way ?
For example :
i2b2.ONT.ctrlr.FindBy = {
clickSearchName: function() {
// do some stuff
i2b2.ONT.ctrlr.FindBy.doNameSearch(search_info); // I tried Step into here
// some more stuff
}
doNameSearch: function(inSearchData) {
// If I set break-point here then only I can debug it
// or it directly takes control to `// some more stuff` in `clickSearchName:function`
}
}
PS: It also more external JS function calls.
Thanks,
Ajinkya.
"Step into" will step into the function if there is JS source for the function. If not (like for document.getElementById("foo"), it will step over it since it doesn't have anything that it understand to step into.
If you can point us to a working example where you are having the problem (either a jsFiddle reduction of the problem or a working web page) with instruction on where the relevant code is, we can probably help more.
Judging by your code example, I'm wondering what you're trying to step into. The line of code that starts with clickSearchName defines a function. It doesn't execute it. So, it won't go into that function until some later code actually calls clickSearchName. So, perhaps you're breaking on the definition of the function and trying to step into the function when it isn't being executed. That's just a guess though since we don't have a working example to try ourselves.
Add the line debugger; to your code at the place where you want to break into the debugger, it's a JavaScript keyword, which should do what you want. Just remember to take it out when you're done debugging your code.
Could someone explain the javascript that makes up Google's Website Optimiser Control script? Specifically: the first two lines, which seem to be empty functions, and why is the third function wrapped parentheses () ?
As far as I can tell this script is basically writing out a new <script> which presumably loads something for A/B testing.
function utmx_section(){}
function utmx(){}
(function() {
var k='0634742331',d=document,l=d.location,c=d.cookie;
function f(n) {
if(c) {
var i=c.indexOf(n+'=');
if (i>-1) {
var j=c.indexOf(';',i);
return escape(c.substring(i+n.length+1,j<0?c.length:j))
}
}
}
var x=f('__utmx'),xx=f('__utmxx'),h=l.hash;
d.write('<sc'+'ript src="'+'http'+(l.protocol=='https:'?'s://ssl':'://www')+'.google-analytics.com'+'/siteopt.js?v=1&utmxkey='+k+'&utmx='+(x?x:'')+'&utmxx='+(xx?xx:'')+'&utmxtime='+new Date().valueOf()+(h?'&utmxhash='+escape(h.substr(1)):'')+'" type="text/javascript" charset="utf-8"></sc'+'ript>')
}
)();
I've attempted to step through with the firebug debugger but it doesn't seem to like it. Any insights much appreciated.
Many thanks
inside anonymous function it shortens names of document and cookies inside it at first, function f(n) gets value of cookie under name n. Then Google reads its cookies and with help of d.write it loads its scripts (as I see they are related to Google Analytic). This way it makes On-Demand JavaScript loading... Actually you load these scripts all the time, Google just needs some additional parameters in url, so this is done this way - save parameters in cookie, which next time are used to get script again.
And finally back to the first two magic lines :) After Google loads its script (after executing d.write), there are some functions which uses utmx and utmx_section, as well as definition of these functions, or better to say overriding. I think they are empty at first just because another function can execute it before its real definition, and having empty functions nothing will happen (and no JS error), otherwise script would not work. E.g. after first iteration there is some data, which is used to make real definition of these functions and everything starts to work :)
The first 2 functions are in fact empty, and are probably overridden later on.
The third function is an anonymous self-executing function. The brackets are a convention to make you aware of the fact that it is self executing.
the "f" function looks up the value given to it in the document's cookies and returns it. Then a new script tag is written to document (and requested from server) with these values as part of its URL.