Not secure in HTTPS Node JS Express APP

While trying to add the SSL to the Node js server, Everything went fine but on calling the API it shows insecure.

var fs = require('fs');
var express = require('express');
var https = require('https');
var path = require('path');

const httpsOptions = {
cert: fs.readFileSync(path.join(__dirname, 'ssl', 'certificate.crt')),
key: fs.readFileSync(path.join(__dirname, 'ssl', 'certificate.key'))
};

var app = express();

https.createServer(httpsOptions, app)
.listen(8089, function () {
    console.log('Serving https://localhost:',8089);
});

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.get('/', function (req, res) {
res.send("welcome");
});

via ArUn