Node.js中Express框架变化还是挺大的。

学习一个还未成熟的技术还是有很大风险的，但也具有挑战。

Express 2.x过渡到Express 3.x

删除的:

 1: res.render() "status" option (use node's res.statusCode= or res.status(code).render(...))
   2: res.render() "charset" option (use res.charset=)
   3: res.local(name, value) (use res.locals.name = value or res.locals({ name: value }) instead)
   4: app.dynamicHelpers() (use middleware + res.locals)
   5: app.helpers() (use app.locals)
   6: the concept of a "layout" (template engine specific now)
   7: partial() (template engine specific)
   8: res.partial()
   9: "view options" setting, use app.locals
  10: "hints" setting
  11: req.isXMLHttpRequest (use req.xhr)
  12: app.error() (use middleware with (err, req, res, next))
  13: req.flash() (just use sessions: req.session.messages = ['foo'] etc)
  14: connect-flash can be used as middleware to provide req.flash()

1: req.header(field[, defaultValue]) replaced by req.get(field) (remains for backwards compatibility)
   2: res.header(field[, value]) replaced by res.set(field, value) / res.get(field) (remains for backwards compatibility)
   3: res.send(body[, code]) is now res.send([code,] body)
   4: res.redirect(url[, code]) is now res.redirect([code,] url)
   5: res.json(obj[, code]) is now res.json([code,] obj)
   6: renamed app.register() to app.engine()
   7: template engine compliance from engine.compile(str, options) => Function to engine.__express(filename, options, callback)
   8: express.createServer() is now simply express() (but remains for BC)
   9: Use express.cookieParser('secret') instead of passing the secret to the express.session() middleware. The 'secret' option in the express.session() middleware has been removed.