Mastering AWS S3 with JavaScript: S3Client Config & Most Useful Commands 🚀

Whether you're building a full-stack app or managing static assets, Amazon S3 is a go-to service for scalable storage. In this post, we’ll break down:

📦 S3Client setup (with @aws-sdk/client-s3)
⚙️ Most useful operations: creating/deleting buckets, uploading/downloading files
🔁 A simple workflow you can apply to your own app

🔧 Setting Up the AWS S3 Client

First, install the SDK:

npm install @aws-sdk/client-s3

Then configure your client:

// config/s3Client.js
import { S3Client } from '@aws-sdk/client-s3';

const s3Client = new S3Client({
  region: 'your-region', // e.g., 'us-east-1'
  credentials: {
    accessKeyId: process.env.AWS_ACCESS_KEY_ID,
    secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY
  },
});

export default s3Client;

💡 Best Practice: Store your credentials securely using environment variables or IAM roles (if you're using Lambda/EC2).

📚 Most Useful S3 Commands

✅ 1. Create a Bucket

import { CreateBucketCommand } from '@aws-sdk/client-s3';

await s3Client.send(new CreateBucketCommand({
  Bucket: 'my-awesome-bucket',
}));

🗑️ 2. Delete a Bucket

import { DeleteBucketCommand } from '@aws-sdk/client-s3';

await s3Client.send(new DeleteBucketCommand({
  Bucket: 'my-awesome-bucket',
}));

📤 3. Upload an Object

import { PutObjectCommand } from '@aws-sdk/client-s3';
import fs from 'fs';

const fileStream = fs.createReadStream('./example.txt');

await s3Client.send(new PutObjectCommand({
  Bucket: 'my-awesome-bucket',
  Key: 'example.txt',
  Body: fileStream,
}));

📥 4. Download an Object

import { GetObjectCommand } from '@aws-sdk/client-s3';
import fs from 'fs';

const response = await s3Client.send(new GetObjectCommand({
  Bucket: 'my-awesome-bucket',
  Key: 'example.txt',
}));

response.Body.pipe(fs.createWriteStream('./downloaded.txt'));

❌ 5. Delete an Object

import { DeleteObjectCommand } from '@aws-sdk/client-s3';

await s3Client.send(new DeleteObjectCommand({
  Bucket: 'my-awesome-bucket',
  Key: 'example.txt',
}));

📃 6. List Objects in a Bucket

import { ListObjectsV2Command } from '@aws-sdk/client-s3';

const response = await s3Client.send(new ListObjectsV2Command({
  Bucket: 'my-awesome-bucket',
}));

console.log(response.Contents);

🧠 Workflow Example: Image Upload API

Here’s a simple idea of how your workflow could look in a backend:

User uploads an image
Frontend sends file to backend
Backend uploads file to S3
S3 returns URL
URL saved in DB
URL sent back to frontend

// Upload and return URL
const uploadToS3 = async (file, key) => {
  await s3Client.send(new PutObjectCommand({
    Bucket: 'my-awesome-bucket',
    Key: key,
    Body: file.buffer,
    ContentType: file.mimetype,
  }));

  return `https://${yourBucket}.s3.${yourRegion}.amazonaws.com/${key}`;
};

🧪 Extra Commands to Explore

CopyObjectCommand – Duplicate files
HeadObjectCommand – Check if file exists
PutObjectAclCommand – Make file public
Multipart Upload – For large files (>5MB)

✅ Final Thoughts

The AWS SDK v3 makes working with S3 modular and easy. With the right config and a clean workflow, integrating S3 into your app is seamless. If you’re building a file uploader, static hosting solution, or media management API—this toolkit is all you need to start strong.

💬 Have questions or want to see this workflow in Express, Next.js, or NestJS? Drop a comment!

Shubham Bhilare @shubham_bhilare_3611