README.md

@bogeychan/elysia-etag

A plugin for Elysia.js for automatic HTTP ETag generation

Installation

bun add @bogeychan/elysia-etag

Usage

import { Elysia } from 'elysia'
import { etag } from '@bogeychan/elysia-etag'

const app = new Elysia()
	.use(etag())
	.get('/', () => 'Checkout the response headers!')
	.get('/custom-etag', (ctx) => {
		// This line disables automatic ETag generation
		// It will still return a 304 - Not Modified - status code if the ETag matches
		ctx.setETag('"myETag"')
		return 'Hello ETag!'
	})
	.listen(3000)

console.log(`Listening on ${app.server!.url}`)

Use serialize to convert incompatible data to a hashable format

With JSON

new Elysia()
	.use(
		etag({
			serialize(response) {
				if (typeof response === 'object') {
					return JSON.stringify(response)
				}
			}
		})
	)
	.get('/', () => ({ my: 'json' }))

With BunFile

new Elysia()
	.use(
		etag({
			serialize(response) {
				if (response instanceof Blob && 'lastModified' in response) {
					// based on last modified UNIX timestamp
					return (response as BunFile).lastModified.toString()

					// based on file content
					return (response as BunFile).bytes()
				}
			}
		})
	)
	.get('/', () => Bun.file('./file.txt'))

Provide your own hash function

let myInsecureChangeCounter = 0

new Elysia()
	.use(
		etag({
			hash(response) {
				return (response as string) + myInsecureChangeCounter++
			}
		})
	)
	.get('/', () => 'Checkout the response headers!')

Checkout the examples folder on github for further use cases.

Credits ❤️

This project was inspired by @fastify/etag

License

MIT