I have a nodejs server (sockjs) not fully developed by me. At a certain point a function is called, but I could go back to where the function is defined (if it belongs to a certain module, official or custom)
There's a programmatical way to know where a certain function is defined?
You should use a debugger. This would allow you to put breakpoints, so you can locate where that specific function is called and go into.
There are plenty of IDEs, I am familiar with Webstorm (the debugger works well).
Related
is there any option to set something like "breakpoint" on a file in chrome console (kindof shortcut to set breakpoint on every line of code in the file)?
Would be extremely useful when trying to understand 3rd party scripts that you know are executed but have no idea which part of code and from where is executed when.
My current example use case: I downloaded a script (form validation) which does not work as expected. The fastest way to solve the problem would be to pause execution anytime JS runtime enters this file and start exploring it from there.
I think this will be of use to you. I've recently been doing some work on the JavaScript Breakpoint Collection Chrome Extension created by Matt Zeunert, which allows you to inject breakpoints into your code at runtime - including breaking on property access/modifications, functions, scrolling events, etc. You can break on any arbitrary objects as well as the predefined ones using the console API.
Check out the project here.
If you can enumerate the functions publicly exposed by your third party script (for example if they are all properties of an object, or is their name has a pattern) you can make another script which dynamically replaces all those functions and force a break point :
thirdpartfunc = (function () {
var oldfunc = thirdpartfunc;
return function () {
debugger;
oldfunc.call(null, arguments);
}());
With the appropriate binding to this (if any applicable).
If you know the function(s) being called, you can use function breakpoints
debug(function);
function(...args);
When you call the function, it will hit the breakpoint. These aren't saved on page reload, but you can set a line breakpoint once you hit the function breakpoint.
This can get kinda tedious though.
If you have a array of functions, you can do
[function0, function1].map(debug)
#Tibos answer in another post would be good if there was some sort of babel transform to insert debugger; at the start of every function, instead of inserting it manually.
The quickest way for me was to do a global replace of the function declarations in the source, adding "debugger;" at the start.
In other words, replace
function [^{]*{
with
$0 debugger;
Your regexp may vary depending on the escapes you need. For example:
function [^{]*\{
You may also need more than one pattern to handle all the function declarations you have.
This has nothing to do with the Chrome console though.
No. You would have to add breakpoints to the various function entry points that file contains to catch everywhere it could enter.
Can't you just place a breakpoint at the first line of every function in the file of interest?
I'm trying to understand how a webpage works. When you click a button, they call a function from javascript, with some arguments, just like this <a href="javascript:ShowListing('24343434', 22, '2', '434331')" class="btn">. The function (in an external .js) looks like this:
function ShowListing(id1,id2,id3,id4) {
somecode here
Dialog.Show( id1, assets[id2][id3][id4] );
}
My question is, what's assets? I looked for the declaration of the variable in all the scripts and I couldn't find it. Maybe it's defined in a .php?
Is there any way of knowing the value it has given some specific [ids]?
Thanks!
My question is, what's assets?
A variable containing an object of some sort. We can't tell any more than that from the code you've supplied.
I looked for the declaration of the variable in all the scripts and I couldn't find it. Maybe it's defined in a .php?
It has to be defined by client side JavaScript (unless it is a browser built-in which I don't recognise, but seems highly unlikely given the context it is used in). That JS could be in a .php file.
Is there any way of knowing the value it has given some specific [ids]?
Just about every modern browser has a Developer Tools feature.
Developer Tools come with a JavaScript debugger that lets you set breakpoints.
Set a breakpoint to that line and then you can examine the variables in it using the debugger.
Search terms such as how to use the chrome developer tools debugger will help you learn to use those tools for your browser.
First hit F12 if you're on firefox (i think the same goes for chrome) the console panel should be visible, then add the console.log() and refresh the page to see what is asset use
console.log(assets);
the same goes for the other ids and the value of each array in assets
An old web application I recently have to work with is having an issue. There is an input element that contains the following:
onClick="javascript:Run('**SomeFilePath.mdb**');"
What this is supposed to do is open a users respective .mdb file.
First off, there is no javascript Run function defined anywhere. I searched online because I thought maybe it's an old javascript built-in, but I couldn't find anything.
Second off, there IS a vbscript Run() function, that implements the described behavior, defined in the source code, but as far as I know javascript can't call that other than via ajax, which as you can see isn't what is happening.
The strange part is this works for some users!
If anyone could shed some light as to why I'd appreciate it!
EDIT: The only browser I'm dealing with is IE. I know there is an active-x way to open a file, which is what the vbscript Run() function I mentioned above is using.
Update: So after more investigation/research, it would seem like when IE doesn't find the javascript Run() function it defaults to the vbscript Run() function that IS defined. However this only occurs on some versions of IE. Can anyone confirm this behavior?
Research links:
Comment referring to how IE defaults w/ scripting
Msdn article about using both script types in same page
Yes, you can run vbscript from javascript and vice-versa, i do it sometimes when one language doesn't support something the other does.
You can indicate in your script which is the default language in case you don't specify it like .
You can also specify it while calling the function like vbscript:functionname("..") or javascript:functionname("..")
As you noticed there are cases where the browser gets confused and doesn't find the function because he searches/executes the function in the wrong language.
This behavior is influenced i suppose by version also but surely by in which order the logic flows in your script, if the browser first executes a javascript he tends to go further in this language in case of doubt.
So to evade this
don't mix the two unless realy necessary, translate your vbscript function in javascript)
try to always use javascript, vbscript is less good at handling DOM etc
in case they are mixed, specify the correct scriptlanguage when you call a function
when opening a script tag, also give the correct language like or
So, specific, to solve your problem translate the vbsripts function to javascript and if not possible, call your function like onClick="vbscript:Run('**SomeFilePath.mdb**')"
we have developed an Intranet Management Application with Silverlight 4. We have been asked to add the functionality to call a remote desktop tool which is installed on clients using the Intranet SL App. In an earlier version of the tool written in ASP.NET we just added a Javascript function to the aspx page like this:
function RunShellCommand()
{
var launcher = new ActiveXObject("WScript.Shell");
launcher.Run("mstsc.exe");
}
and called it from ASP.NET.
Now it's clear that SL4 is running in a sandbox and that I cant use the AutomationFactory to create a WScript.Shell object (out of browser mode is not an option).
I thought I could circle around the problem by, again, adding the RunShellCommand javascript method in the aspx page where the SL4 control is hosted and call it via
HtmlPage.RegisterScriptableObject("Page", this);
HtmlPage.Window.Invoke("RunShellCommand", "dummydata");
from my ViewModel. When I run the Application the debugger just skips the RegisterScriptableObject method and quits. Nothing happens.
My question is if am doing something wrong or if this just wont work this way.
Is it possible that I cant do a RegisterScriptableObject from a viewmodel?
EDIT: When I explicitly put a try, catch block around the two methods I get an ArgumentException from the first method stating that the current instance has no scriptable members. When I delete the first method and only run the Invoke, I get a browser error stating that the automation server cant create the object. So is there really no way (except OOB mode) to do this?
Yes, the explanation is correct: you should add at least one method with the ScriptableMember attribute in order that you can use the RegisterScriptableObjectmethod. But it is used only for calling C#-methods from JavaScript.
As far as I see, you want to do the opposite: to call JavaScript code from the Silverlight application. Then you need only one line:
HtmlPage.Window.Invoke("RunShellCommand");
The error automation server cant create the object has nothing to do with Silverlight. I'm sure that if you call the JS function directly - the error will remain.
According to the internet, the reason might be not installed Microsoft Windows Script. Or it is because of security restrictions of the browser.
I tried to create custom widget for my site. when I loaded page it says:
mixin #0 is not a callable constructor.
clsInfo.cls.prototype is undefined
I can't find any information about clsInfo, so I don't know what is it. maybe the problem that I use dojo from google:
and my own script is located on localhost. so when my dojo on page initializes something goes wrong with my script. I can't find any good info on dojo, maybe I search in wrong places?
please help me to resolve my problem
I ran into this when I was trying to override a dijit.Dialog so I could bind events to controls within it. We've yet to see if the binding part will work, but if you look at the source, this happens when one of the bases passed in as the second argument fails to resolve to an "[Object function]". In my case, I was passing a String in.
dojo.declare takes 3 arguments:
The name of the custom object "class" you're building
An array of base classes, parents to provide functionality (not the string names of those classes)
A hash of functions and declarations
So if I want to override dijit.Dialog, I have to do:
dojo.declare("myDialogType", [dijit.Dialog], {
function1() {/*Code*/},
function2() {/*Code*/}
}
I had ["dijit.Dialog"] as my second argument and that was the problem.
I strongly recommend using Web Inspector or Firebug with uncompressed local copies of the Dojo library rather than the CDN to figure out what's going on and debug these types of problems. Dojo's documentation is extensive but not complete in some areas and some behaviors have to be figured out by looking at what the code expects. That's not intended as a slight to the authors; once you get it going it's a pretty awesome product, and any documentation for volunteer work is appreciated.
Are you sure Dojo is loading? Did you put your code in a dojo.addOnLoad()? When using a CDN you sometimes run into issues with execution times. dojo.addOnLoad() will not only trigger when the DOM is loaded, it gets called when dojo resources have downloaded, such as dijit._Widget.
I've run into this problem when I screw up the order of my requires which makes _WidgetBase not what _WidgetBase really is. Seems like a simple spot to screw up.