The line # isn't so useful when your page is dynamically generated. What I'd really like is the actual offending line.
Is there some way of doing this? Perhaps
document.getElementsByTagName('html')[0].innerHTML.Split('\n')[lineNumber-1];
// OR
document.body.innerHTML.Split('\n')[lineNumber-1];
However, when I tested it in Firefox 10, I got that the above were inaccurate unless the html and body tags were on the same line.
Thanks in advance.
For anyone who is curious, the answer for me was to make the number of lines above the first head or body element consistent across all pages.
For me this magic # is three.
One should note though that if the error occurred in a js file, then I don't know how to get the actual line client-side. However, since the whole point of this was to log the line to the server (using ajax), I could simply read the line of the js file on the server. So it means that you have to ad an extra check on the url of the error to see that it is or is not a javascript file.
Related
firstly very sorry, I cant find out what the real problem is.
I ll try to explain.
My client given code which is developed using opencart and nitropack.
he includes common.js in header, it is basic js file with some ajax calls, UI events etc which has 1297 lines(no formating in code, lots of blank spaces, blank lines etc).
my real problem is, when I made any changes in this file,
the browser console is throwing error invalid or unexpected token.
I checked the common.js file in browser console, seeing that some kind of reddots added at last of the file. I just added a alert() at the begining of file. nothing else.
very sorry, dont know how to explain more detaily.
This is the first time I have seen this kind of issue.
when I removed the alert(), the error gone.
I just got some big project and with error in console. there are many more than scripts used at that page but error shows very little information. there are 25 scripts loading at page. To give you an idea how many scripts they are you can see. :(
I have error in console but i can't find which original file, line number causing it. the error showing are in library. but i know it's not library bug it's caused by some other script. but this stack trace is very small. is there any tool or any other way where i can originally find from where it is originating.
let me know if further information is required.
If you click on link "amstock.js" you will be redirect to that file and directly in the line that was causing the error. Always the upper file is which causes the problem, but some times because of a previous one.
In adition, the error maybe cause by an asynchronous call that leaves your variable in null and fill it after the line of the error was call, or just you are trying to access a wrong variable. Check that line.
When catching an error, I want to get with the stack trace the actual code of the line that triggered the error.
Given that I have the path to the file and the line number throwing the error, what's the best way to also get the actual code of that line?
Beyond the obvious of "looking it up in the file", there are a few things you can do to get it automatically. Checkout the Tracekit project on GitHub. For errors it captures, it will do an AJAX request for the script and find the relevant lines in the text.
Alternatively, if you're looking for a way to handle this automatically, you should consider a service like TrackJS that will capture all the relevant scripts and apply sourcemaps for you. I am one of the original developers and I've used it on many projects to fix bugs ridiculously fast :)
I am finding it difficult to locate where an error occurs in javascript on a client I have no access to. Currently I trap the error with onerror and send the arguments to a log on the server.
Unfortunately the line number is no help because numerous javascript files get included, causing the line number to not correspond to anything I have access to.
So if I get something like "n is not defined", and n occurs many times in the function, I have no way to locate where it happened.
I have been trying to reference the code on the line throwing the error say "x=n * 5 + 4", then I could search for that code, but have had no luck referencing the actual code on a line from within javascript.
So how does one locate the line that threw the error in this situation?
client uses firefox only, if that matters.
I have no access to client
This is not one error I am stuck on, but working on how to track an error in this situation
Your best bet would be to use Firefox's debugger.
Open dev tools
Go to the debugger, select the .js file you want, and hit the little {} button in the bottom left (depending on version yours may be in a different location) -- this will prettify the JavaScript
Set breakpoints by clicking next to line numbers
From here on out you have to do this old-fashioned. Cast a breakpoint net around your trouble code, then keep narrowing down the lines until you find the occurrence that causes the error.
Of course, once you find the line it still won't be 1-to-1 with the original code, but hopefully the breakpoint exercise will at least reduce the scope of code/logic you have to dig through.
use your debugger to enable breaking on error. once you break, look at your locals for clues about your location. go up the stack and look at each frame.
you should be able to trace n up the stack and find out why it was null
the little {} that william suggested is also helpful
I was working on something in PHP and I wanted to include a file and insert something at the end. Without thinking about it, I did the include and then echoed out the material I wanted to insert, which was a JS script.
When I looked at the output, I realized I had forgotten about the tags in the included file. The script was inserted after them, but surprisingly (at least to me) it was executed.
Had you asked me before I did this if a script after the and tags would execute, I would have said "I don't think so." I would have said that I thought it would not execute because I had assumed, up to now that anything after the and tags is ignored by browsers.
So, had you asked, I would have given that answer and I would have been quite wrong.
A script placed after the and tags does execute - why?
I've tried it with FF 3.6.24 and I.E 8.0.7601.17514 and it behaves the same in both.
Any text after the and tags is displayed - why?
Does anyone have any thoughts on this? And, is this something I might be able to rely upon? If so, I can simplify some processing, here and there.
Here's the page I was playing with http://www.bobnovell.com/PastHtmlEndTesting.shtml - let me know if your particular browser does not execute the script and/or display the text that I've put after the script.
Bob
This is well specified behavior in HTML5 though it will be flagged by an HTML5 validator.
The after after body insertion mode defines what happens to content that is after the </html> tag. The rule that handles this case is:
Anything else
↪ Parse error. Switch the insertion mode to "in body" and reprocess the token.
So techinically, it's a parse error, but one with well defined behavior. The <script> element is parsed and executed as if it had appeared in the body, and the element should appear in the DOM in the body.
Most browsers will not treat "parse errors" as fatal. The HTML 5 spec explains:
Certain points in the parsing algorithm are said to be parse errors. The error handling for parse errors is well-defined: user agents must either act as described below when encountering such problems, or must abort processing at the first error that they encounter for which they do not wish to apply the rules described below.