cannot-set-headers-after-they-are-sent-to-the-client.js

example.js

// exmaple.js
var express = require('express')
var app = express()

app.get('/foo', function (req, res) {
  res.redirect(301, '/bar')
  res.send('hello world') // should not set body while redirect in flight
})


app.listen(3000)

// › node example.js
// Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
//     at ServerResponse.setHeader (_http_outgoing.js:485:11)
//     at ServerResponse.header (/Users/lfender/source/ag.js/node_modules/express/lib/response.js:771:10)
//     at ServerResponse.send (/Users/lfender/source/ag.js/node_modules/express/lib/response.js:170:12)
//     at /Users/lfender/source/ag.js/example.js:6:7
//     at Layer.handle [as handle_request] (/Users/lfender/source/ag.js/node_modules/express/lib/router/layer.js:95:5)
//     at next (/Users/lfender/source/ag.js/node_modules/express/lib/router/route.js:137:13)
//    at Route.dispatch (/Users/lfender/source/ag.js/node_modules/express/lib/router/route.js:112:3)
//    at Layer.handle [as handle_request] (/Users/lfender/source/ag.js/node_modules/express/lib/router/layer.js:95:5)
//    at /Users/lfender/source/ag.js/node_modules/express/lib/router/index.js:281:22
//    at Function.process_params (/Users/lfender/source/ag.js/node_modules/express/lib/router/index.js:335:12)