uploadToS3.js

const s3 = new AWS.S3({
    accessKeyId: process.env.AWS_ACCESS_KEY,
    secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY,
});

const uploadFile = () => {
    fs.readFile(file.filepath, (err, data) => {
        if (err) {
            res.status(400).send(ApiResponse({}, err.message, false));
        }
        const params = {
            Bucket: "bucket-name", // pass your bucket name
            Key: fileName, // file will be saved as testBucket/contacts.csv
            Body: JSON.stringify(data, null, 2),
        };
        s3.upload(params, function(s3Err, data) {
            if (s3Err) {
                res.status(400).send(ApiResponse({}, s3Err, false));
            }
            console.log(`File uploaded successfully at ${data.Location}`);
            fields.document = data.Location;
        });
    });
};