Adapter Helper

Runtime detection and environment access

The Adapter Helper provides utilities for detecting the runtime environment and accessing environment variables.

Import

import { env, getRuntimeKey } from 'hono/adapter'

Functions

env()

Get environment variables and bindings in a type-safe way.

function env<T extends Record<string, any> = Record<string, any>, C extends Context = Context>(
  c: C
): T & C['env']['Bindings']

c · Context · required

The context object

return · T & Bindings

Environment variables and bindings

Example

import { env } from 'hono/adapter'

app.get('/', (c) => {
  const { DATABASE_URL, API_KEY } = env(c)
  return c.text(`Using database: ${DATABASE_URL}`)
})

getRuntimeKey()

Detect the current JavaScript runtime.

function getRuntimeKey(): 
  | 'node' 
  | 'deno' 
  | 'bun' 
  | 'workerd' 
  | 'fastly' 
  | 'edge-light' 
  | 'other'

return · RuntimeKey

The detected runtime key

Example

import { getRuntimeKey } from 'hono/adapter'

const runtime = getRuntimeKey()
console.log(`Running on ${runtime}`)

if (runtime === 'deno') {
  // Deno-specific code
} else if (runtime === 'bun') {
  // Bun-specific code
}

Type-Safe Environment

import { env } from 'hono/adapter'

type Env = {
  Bindings: {
    DATABASE_URL: string
    API_KEY: string
  }
}

app.get('/', (c) => {
  const { DATABASE_URL, API_KEY } = env<Env['Bindings']>(c)
  // TypeScript knows these are strings
})