console.log to your node app

app.js

// In your connect middleware setup in development mode
app.use(require("./lib/console.log.remote/middleware")());

// Your pages will have to include /console.log.js to override console.log

client.js

window.console = window.console || {}
window.console.actual_log = window.console.log || function(){};
window.console._sprintf = function(format){
  var return_str = new String(format);
  var match;
  var reg = /%([osif])/i;
  var before, after, replacement;
  var argIndex = 1;
  do {
    match = reg.exec(return_str);
    if(match){
      before = return_str.substr(0, match.index);
      after = return_str.substr(match.index + match[0].length, return_str.length);
      replacement = "";
      switch(match[1]){
        case "o":
          if(window.JSON && window.JSON.stringify){
            replacement = JSON.stringify(arguments[argIndex]);
          } else {
            replacement = arguments[argIndex].toString();
          }
          break;
        case "i":
          replacement = parseInt(arguments[argIndex]).toString()
          break;
        case "f":
          replacement = arguments[argIndex].toFixed(3)
          break;
        case "s":
          replacement = String(arguments[argIndex])
      }
      return_str = before + replacement + after;
      argIndex ++ ;
    }
  } while(match);
  return return_str;
};
window.console.log = function(format){
  var to_server = window.console._sprintf.apply(null, arguments);
  window.console.actual_log.apply(window.console, arguments);
  var req = new XMLHttpRequest();
  req.open("POST", "/console.log", true);
  req.setRequestHeader("Content-type", "text/plain");
  req.send(to_server);
}

middleware.js

var fs = require("fs");

var remote_console_log_js = fs.readFileSync(__dirname + "/client.js");
module.exports = function(){
  return function(req, res, next){
    if(req.url == "/console.log.js" && req.method == "GET"){
      res.writeHead(200, { 'Content-Type' : 'text/javascript' })
      res.end(remote_console_log_js);
    } else if(req.url == "/console.log" && req.method == "POST"){
      var data='';
      req.setEncoding('utf8');
      req.on('data', function(chunk) { 
         data += chunk;
      });

      req.on('end', function() {
        console.log("console.log: [", 
                      new Date().getTime(), 
                      req.connection.remoteAddress,
                      req.header("User-Agent").substring(0, 64) + "...",
                      "]: ", 
                      data);
        res.writeHead(200, { 'Content-Type' : 'text/plain' })
        res.end("OK");
      });
    } else {
      next();
    }
  };
};