jQuery event handlers to prevent logging after the window goes crazy! =)

globalErrorHandlerHookup.js

(function($, window, undefined) {
    
    // WARNING! Set this as you see fit
    var suppressUnhandledErrors = true;

    var okToLogErrors = true;
    var isOnline = true;
    var offlineErrorQueue = [];

    var logError = function(err) {
        if (!okToLogErrors) {
            return;
        }

        if (!isOnline) {
            offlineErrorQueue.push(err);
            return;
        }

        // Fire and forget
        $.ajax({
            type: 'POST',
            url: '/errors',
            dataType: 'application/json',
            data: JSON.stringify(err)
        });
    };

    // Handle unhandled JavaScript errors
    window.onerror = function(errorMsg, url, lineNum, columnNum) {
        var err = new Error(errorMsg);
        err.name = "UnhandledError";
        err.fileName = url || window.location.href;
        err.lineNumber = lineNum || 0;
        err.columnNumber = columnNum || 0;
        err.stack = null;

        logError(err);

        // Let the browser keep trying to execute JavaScript by suppressing ("handling") the error?
        return suppressUnhandledErrors;
    };

    var $win = $(window);
    $.each(['abort', 'cancel', 'stalled', 'suspended', 'unload'], function(i, e) {
        $win.on(e, function() {
            okToLogErrors = false;
        });
    });

    $(window.document).on('error', function(err) {
        err.fileName = err.fileName || window.location.href;
        err.lineNumber = err.lineNumber || 0;
        err.columnNumber = err.columnNumber || 0;
        err.stack = err.stack || null;

        logError(err);
    });

    $win.on('offline', function() {
        isOnline = false;
    });

    $win.on('online', function() {
        isOnline = true;

        $.each(offlineErrorQueue, function(i, e) {
            logError(e);
        });
        offlineErrorQueue.length = 0;
    });
})(jQuery, this);

If you want to get really "crazy" cough AWESOME cough, you could also take it one step further by overriding jQuery's on method to essentially add a try-catch construct internally, a la http://forum.jquery.com/topic/catching-all-errors

Oh, and you may also find the addition of a library like StackTrace.js to be useful (despite its currently terrible API 😢).

This is pretty brilliant...love the online/offline handling!

Out of curiosity, why JSON.stringify(err) rather than pass err directly?