How to catch and log every PHP and JS error in production website?

I have a website that's written in PHP and uses intense level of JS coding. One of my clients has a very strange error. The site is empty and nothing is displayed. I can not reproduc开发者_开发百科e the error in spite i use the same browser, the same OS and have much the same addons and firewall and antivirus.

So i would like to catch every one PHP and JS error or warning and put it in the error log (best - to database). Is there any ready, simple solution to acomplish this? I address this question to experienced web-developers.

Or is there any way to dump every data about user session while the error occurs that is easy to acomplish by no-tech user? I see it this way: when the user has this error, he clicks something (for example in extension or something) and this sends all session, error informations to me so I can figure out what is going on. Do you know any solution of this kind?

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mplungjan's idea is good.

I would also ask the client to view the source of the page and send that to me to make sure it looks OK.

Your web server (e.g. apache) should keep a log file of every single PHP request and tell you whether errors occurred.

I don't know if there is a way to report javascript errors back to your server. If you were able to catch the error and send an AJAX request in your error handler to get logged on your server, that would work. But I think that some javascript errors (like syntax errors?) can not be caught with catch. I would ask the client to open the javascript console (or whatever it is called in his browser) and tell me all the errors he sees. You should eliminate all the errors eventually, and a good strategy to do that would be to focus on the first error that occurred.

I would run the page through a w3c validator to see if it is valid HTML/CSS.

Also, you should try the universal technique of simplifying the code down to the simplest possible thing that should work but doesn't work. That will either let you find the problem or produce something that is so small and simple that you can post it to Stack Overflow.

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You need to differ between two types of errors: Client-side and Server-side.

A blank page can be both, but I would think most likely this is server-side.

For server-side errors you can log every error and even add own information like the session by registering your own error handler. You then can log errors into the database and append the session and request information as well as providing a backtrace. This will enable you to obtain more information.

For client side, David Grayson's answer has a suggestion.