Started on node.js+socket.io+mongoDB on the backend for more responsivnes

server/node_modules/express/node_modules/finalhandler/index.js

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+/*!
+ * finalhandler
+ * Copyright(c) 2014 Douglas Christopher Wilson
+ * MIT Licensed
+ */
+
+/**
+ * Module dependencies.
+ */
+
+var debug = require('debug')('finalhandler')
+var escapeHtml = require('escape-html')
+var http = require('http')
+var onFinished = require('on-finished')
+
+/**
+ * Variables.
+ */
+
+/* istanbul ignore next */
+var defer = typeof setImmediate === 'function'
+  ? setImmediate
+  : function(fn){ process.nextTick(fn.bind.apply(fn, arguments)) }
+var isFinished = onFinished.isFinished
+
+/**
+ * Module exports.
+ */
+
+module.exports = finalhandler
+
+/**
+ * Final handler:
+ *
+ * @param {Request} req
+ * @param {Response} res
+ * @param {Object} [options]
+ * @return {Function}
+ * @api public
+ */
+
+function finalhandler(req, res, options) {
+  options = options || {}
+
+  // get environment
+  var env = options.env || process.env.NODE_ENV || 'development'
+
+  // get error callback
+  var onerror = options.onerror
+
+  return function (err) {
+    var msg
+
+    // ignore 404 on in-flight response
+    if (!err && res._header) {
+      debug('cannot 404 after headers sent')
+      return
+    }
+
+    // unhandled error
+    if (err) {
+      // default status code to 500
+      if (!res.statusCode || res.statusCode < 400) {
+        res.statusCode = 500
+      }
+
+      // respect err.status
+      if (err.status) {
+        res.statusCode = err.status
+      }
+
+      // production gets a basic error message
+      var msg = env === 'production'
+        ? http.STATUS_CODES[res.statusCode]
+        : err.stack || err.toString()
+      msg = escapeHtml(msg)
+        .replace(/\n/g, '<br>')
+        .replace(/  /g, ' &nbsp;') + '\n'
+    } else {
+      res.statusCode = 404
+      msg = 'Cannot ' + escapeHtml(req.method) + ' ' + escapeHtml(req.originalUrl || req.url) + '\n'
+    }
+
+    debug('default %s', res.statusCode)
+
+    // schedule onerror callback
+    if (err && onerror) {
+      defer(onerror, err, req, res)
+    }
+
+    // cannot actually respond
+    if (res._header) {
+      return req.socket.destroy()
+    }
+
+    send(req, res, res.statusCode, msg)
+  }
+}
+
+/**
+ * Send response.
+ *
+ * @param {IncomingMessage} req
+ * @param {OutgoingMessage} res
+ * @param {number} status
+ * @param {string} body
+ * @api private
+ */
+
+function send(req, res, status, body) {
+  function write() {
+    res.statusCode = status
+
+    // security header for content sniffing
+    res.setHeader('X-Content-Type-Options', 'nosniff')
+
+    // standard headers
+    res.setHeader('Content-Type', 'text/html; charset=utf-8')
+    res.setHeader('Content-Length', Buffer.byteLength(body, 'utf8'))
+
+    if (req.method === 'HEAD') {
+      res.end()
+      return
+    }
+
+    res.end(body, 'utf8')
+  }
+
+  if (isFinished(req)) {
+    write()
+    return
+  }
+
+  // unpipe everything from the request
+  unpipe(req)
+
+  // flush the request
+  onFinished(req, write)
+  req.resume()
+}
+
+/**
+ * Unpipe everything from a stream.
+ *
+ * @param {Object} stream
+ * @api private
+ */
+
+/* istanbul ignore next: implementation differs between versions */
+function unpipe(stream) {
+  if (typeof stream.unpipe === 'function') {
+    // new-style
+    stream.unpipe()
+    return
+  }
+
+  // Node.js 0.8 hack
+  var listener
+  var listeners = stream.listeners('close')
+
+  for (var i = 0; i < listeners.length; i++) {
+    listener = listeners[i]
+
+    if (listener.name !== 'cleanup' && listener.name !== 'onclose') {
+      continue
+    }
+
+    // invoke the listener
+    listener.call(stream)
+  }
+}