i have follow codes used middlewares
module.exports=function(callback) { callbacks.push(callback); return function(req,res,next) { if (!res.hijacked) { res.hijacked=true; } else { return next(); } var send=res.send; res.send=function(data) { var body=data instanceof buffer ? data.tostring() : data; var requests=[]; requests.push(function(next) { callbacks[0](req,res)(body,donewrapper(body,next)); }); (var i=1;i<callbacks.length;i++) { var hijackcallback=callbacks[i]; requests.push(function(result,next) { hijackcallback(req,res)(result,donewrapper(result,next)); }); } var that=this; async.waterfall(requests,function(err,result) { send.call(that,result); requests=null; body=null; that=null; }); }; next(); }; }; an example of usage following:
module.exports=function() { return hijack(function() { return function(result,done) { var json={}; try { json=json.parse(result); } catch(e) { return done(); } if (!_.isarray(json)) { return done(); } var sorted=_(json).sortby(function(item) { if (_.isobject(item.information)) { return item.information.rangeindex1 || 999; } else { return 1001; } }); done(sorted); } }); }; it worked fine middlewares in routes.
however,when try make app.use(hijackmiddleware()). went wrong, got can't set headers after sent error.
there no problem when used middlewares in routes,though.
have consider using express-interceptor? easy use:
var express = require('express'); var cheerio = require('cheerio'); var interceptor = require('express-interceptor'); var app = express(); var finalparagraphinterceptor = interceptor(function(req, res){ return { // html responses intercepted isinterceptable: function(){ return /text\/html/.test(res.get('content-type')); }, // appends paragraph @ end of response body intercept: function(body, send) { var $document = cheerio.load(body); $document('body').append('<p>from interceptor!</p>'); send($document.html()); } }; }) // add interceptor middleware app.use(finalparagraphinterceptor); app.use(express.static(__dirname + '/public/')); app.listen(3000); 