index.js

/**
 * Gleak - detect global var leaks.
 * @api public
 */

module.exports = exports = function gleak () {
  return new Gleak;
}

/**
 * Version.
 * @api public
 */

exports.version = '0.1.0';

/**
 * Express middleware.
 * @api public
 */

exports.middleware = function gleakMiddleware (stream, format) {
  var g = new Gleak;

  if (!format) {
    switch (typeof stream) {
      case 'string':
        format = stream;
        stream = process.stderr;
        break;
      case 'undefined':
        format = g.format;
        stream = process.stderr;
        break;
      default:
        format = g.format;
    }
  }

  var known = [];
  setTimeout(print, 1000);

  function print () {
    g.detect().forEach(function (leak) {
      if (~known.indexOf(leak)) return;
      known.push(leak);
      stream.write(format.replace(/%s/, leak) + '\n');
    });
  }

  return function gleakMiddleware (req, res, next) {
    if (res._gleak) return next();
    res._gleak = true;

    var send = res.send;

    res.send = function () {
      res.send = send;
      res.send.apply(res, arguments);
      print();
    }

    next();
  }
}

/**
 * Gleak constructor
 * @api private
 */

function Gleak () {
  this.whitelist = this.whitelist.slice();
}

/**
 * Whitelisted globals.
 * @api public
 */

Gleak.prototype.whitelist = [
    setTimeout
  , setInterval
  , clearTimeout
  , clearInterval
  , console
  , Buffer
  , process
  , global
];

/**
 * Default format.
 * @api public
 */

Gleak.prototype.format = '\x1b[31mGleak!:\x1b[0m %s';

/**
 * Detects global variable leaks.
 * @api public
 */

Gleak.prototype.detect = function detect () {
  var whitelist = this.whitelist
    , ret = []

  Object.keys(global).forEach(function (key) {
    var w = whitelist.length
      , bad = true
      , white

    while (w--) {
      white = whitelist[w];
      if (global[key] === white || 'string' === typeof white && key === white) {
        bad = false;
        break;
      }
    }

    if (bad) ret.push(key);
  });

  return ret;
};

/**
 * Prints all gleaks to stderr.
 * @api public
 */

Gleak.prototype.print = function print () {
  var format = this.format;
  this.detect().forEach(function (leak) {
    console.error(format, leak);
  });
}

/**
 * Add items to the whitelist disallowing duplicates.
 * @api public
 */

Gleak.prototype.ignore = function ignore () {
  var i = arguments.length;
  while (i--) {
    if (~this.whitelist.indexOf(arguments[i])) continue;
    this.whitelist.push(arguments[i]);
  }
  return this;
}