server-logger.js

// IE
if(typeof(window.console) === 'undefined') {
    window.console = {};
    window.console.log = window.console.error = window.console.info = window.console.debug = window.console.warn = window.console.trace = window.console.dir = window.console.dirxml = window.console.group = window.console.groupEnd = window.console.time = window.console.timeEnd = window.console.assert = window.console.profile = function() {};
}

var console = window.console;

// IE8 & 9
var methods = ['log', 'debug', 'info','warn','error','assert','dir','clear','profile','profileEnd'];
if (typeof console.log === 'object' || typeof console.log === 'function') {
    console.debug = console.log;

    _.each(methods, function (method) {
        console['_' + method] = console[method];
    });
}

// Can be customized if needed
console.serverUrl = 'api/log';
console.levels = ['debug', 'info', 'warn', 'error'];
// Disabled by default
console.level = 'off';

var enabledFor = function (level) {
    if(console.level === 'off') return false;
    if (_.indexOf(console.levels, level) === -1) {
        throw new Error('Invalid log level "' + strategy + '", must be one of ' + JSON.stringify(console.levels));
    }
    if (_.indexOf(console.levels, console.level) === -1) {
        throw new Error('Invalid log console.level "' + strategy + '", must be one of ' + JSON.stringify(console.levels));
    }
    return _.indexOf(console.levels, level) >= _.indexOf(console.levels, console.level);
};

var log = console._log;
var debug = console._debug;
var info = console._info;
var warn = console._warn;
var error = console._error;

// console.log = console.debug
console.log = function () {
    Function.prototype.apply.call(log, this, arguments);
    if(enabledFor('debug')) {
        sendLogToServer('debug', arguments);
    }
};
console.debug = function () {
    Function.prototype.apply.call(debug, this, arguments);
    if(enabledFor('debug')) {
        sendLogToServer('debug', arguments);
    }
};
console.info = function () {
    Function.prototype.apply.call(info, this, arguments);
    if(enabledFor('info')) {
        sendLogToServer('info', arguments);
    }
};
console.warn = function () {
    Function.prototype.apply.call(warn, this, arguments);
    if(enabledFor('warn')) {
        sendLogToServer('warn', arguments);
    }
};
console.error = function () {
    Function.prototype.apply.call(error, this, arguments);
    if(enabledFor('error')) {
        sendLogToServer('error', arguments);
    }
};


var sendLogToServer = function(level, msg) {
  var message;
    if((typeof msg === 'object') && (msg.length === 1) && (typeof msg[0] === 'string')) {
        message = msg[0];
    }
    else {
        message = JSON.stringify(msg);
    }

    var log = { 'level':level, 'message': message};
    
    $.ajax({
        type: 'POST',
        url: console.serverUrl,
        data: JSON.stringify(log),
        contentType:'application/json',
        success: function(){
            // update log level
        }
    });
};

// manage global JS errors
window.onerror = function(message, url, linenumber) {
    if(enabledFor('error')) {
        sendLogToServer('error', 'JavaScript error: ' + message + ' on line ' + linenumber + ' for ' + url);
    }
};