How to catch javascript exceptions/errors?

Question

Duplicate:

• Automatic feedback on JavaScript error
• Logging JavaScript-Errors on Server

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How would I go about logging errors in javascript? I can't wrap every line of javascript in try catch block.

I talking about the errors that for example in IE, would show an Error On page message and have the line and char the caused the error. If I can just figure out how to catch this error on the client side, I can just log the error on the server using an ajax call.

Answer 1

I use this function in all my projects:

window.onerror = function(m,u,l){
    jQuery.post("ajax/js_error_log.php",
        { msg: m,
          url: u,
         line: l,
       window: window.location.href });
    return true};

Make sure it is the very first javascript the browser receives or at least precedes any potentially error-causing code. Requires jQuery of course, but you could code ajax functions in pure javascript if you wanted to.

Please note: this will not help you if you have a syntax error. All javascript instantly dies if there is a syntax error.