upload_2.js

const uploadFile = (buffer) => new Promise((resolve, reject) => {
    const bucketName = "YOUR-BUCKET-NAME";
    const fileName =  "YOUR-FILE-NAME.EXTENSION";
    const data = {
        Bucket: bucketName,
        Key: fileName,
        Body: buffer,
    };
    s3.putObject(data, (error) => {
                if (!error) {
                    resolve('success');
                } else {
                    reject(new Error('error during put'));
                }
            });
    });