Create json and upload to s3 bucket using nodejs.

json-to-s3.js

var AWS = require('aws-sdk');
AWS.config.update({ region: 'us-east-1' });
var s3 = new AWS.S3();

var obj = {
    firstname: "Navjot",
    lastname: "Dhanawat"
};

var buf = Buffer.from(JSON.stringify(obj));

var data = {
    Bucket: 'bucket-name',
    Key: 'filename.json',
    Body: buf,
    ContentEncoding: 'base64',
    ContentType: 'application/json',
    ACL: 'public-read'
};

s3.upload(data, function (err, data) {
    if (err) {
        console.log(err);
        console.log('Error uploading data: ', data);
    } else {
        console.log('succesfully uploaded!!!');
    }
});

Thanks brother