How to check if file exists in S3 bucket using AWS SDK for JavaScript

Prerequisites

• "@aws-sdk/client-s3": "^3.38.0" installed
• You have a file named test.txt in your bucket root
• Necessary bucket policy and IAM policy are configured

Use HeadObjectCommand to get metadata

There may be better ways, but below is an example just to get metadata of a file stored in S3 bucket.
It's more efficient than getting actual object if you just want to know the file existence.

import { S3Client, HeadObjectCommand } from "@aws-sdk/client-s3"

// some codes...

const config = {}
const input = {
    Bucket: 'your-bucket',
    Key: 'test.txt'
}
const client = new S3Client(config)
const command = new HeadObjectCommand(input)
const response = await client.send(command)
console.log(response)

response

If you receive status code 200, you're all set.
You will get Not Found error with status code 404 if file does not exist.

{
  '$metadata': {
    httpStatusCode: 200,
    ...