How to enable ocsp in web socket

[LMJayasundara]

I used wb with https and express. Still I get ocsp respond from the ocsp server even I enable ocsp stapling. How to enable it. I coud not figure out it.
This is my code.

var WebSocket = require('ws');
var https = require('https');
var ocsp = require('ocsp');

var bodyparser = require('body-parser');
var express = require('express');
var app = express();

app.use(bodyparser.json());
var PORT = 8080;

var ocspCache = new ocsp.Cache();

var server = new https.createServer({
    cert: fs.readFileSync(`${__dirname}/pki/server/certs/server.cert.pem`),
    key: fs.readFileSync(`${__dirname}/pki/server/private/server.key.pem`),
    ca: [
        fs.readFileSync(`${__dirname}/pki/intermediate/certs/ca-chain.cert.pem`)
    ],
    requestCert: true,
    rejectUnauthorized: true
}, app);

var wss = new WebSocket.Server({
    server
});

wss.on('connection', function connection(ws, req) {

    var cert = req.socket.getPeerCertificate(true);
    var rawCert = cert.raw;
    var rawIssuer = cert.issuerCertificate.raw;

    ocsp.getOCSPURI(rawCert, function(err, uri) {
        if (err) console.log(err);
        var req = ocsp.request.generate(rawCert, rawIssuer);
        var options = {
            url: uri,
            ocsp: req.data
        };
        ocspCache.request(req.id, options, null);
    });

    ws.on('message', function incoming(message) {
        console.log(ocspCache.cache);
        ocsp.check({cert: rawCert, issuer: rawIssuer}, function(err, res) {
            if(err) {
                console.log(err.message);
                ws.send('Failed to obtain OCSP response!');
            } else {
                console.log(res.type);
                var status = res.type;
                if(status == 'good'){
                    console.log('Received: %s', message);
                    ws.send('Hello from server!');
                }else{
                    ws.send('Certificate is revoked!');
                }
            }                              
        });
    });
});

server.listen(PORT, ()=>{
    console.log( (new Date()) + " Server is listening on port " + PORT);
});

@indutny