How to receive data posted by "navigator.sendbeacon" on node.js server?

Question

I am using new browser feature(navigator.sendBeacon) to POST async data to node.js server.

But i am unable to receive it on node server. So could any one tell me how to receive data posted by sendBeacon on node server.

node server code is:

var express = require('express'); var app = express(); var bodyParser = require('body-parser');  // set cross origin header to allow cross-origin request. app.use(function(req, res, next) {   res.header("Access-Control-Allow-Origin", "*");   res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");   next(); });  app.use(bodyParser.json());  app.post('/',function(req,res){     console.log('i got the request',req.body) });  var server = app.listen(3000, function() {     console.log('Express is listening to http://localhost:3000'); }); 

client side code

navigator.sendBeacon('http://localhost:3000/','{"a":9}') 

Answer 1

navigator.sendBeacon POST uses Content-Type:text/plain;charset=UTF-8 to transmit string data. So just add bodyParser.text() to parse 'text/plain' data:

Server:

... app.use(bodyParser.json()); app.use(bodyParser.text()); ... 

Client:

navigator.sendBeacon('http://localhost:3000/', JSON.stringify({a:9})); 

Update

Apparently you can use Blob to add Content-Type:application/json header in your request:

Client:

var blob= new Blob([JSON.stringify({a:9})], {type : 'application/json; charset=UTF-8'}); // the blob navigator.sendBeacon('http://localhost:3000/', blob )