Azion unenv Preset

Use unenv polyfills for Node.js compatibility with Azion Runtime.

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A preset configuration for unenv that provides polyfills and environment compatibility for Azion Runtime.

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Usage

The preset can be used with unenv to provide compatibility between Node.js and Azion Runtime environments:

import { preset } from 'azion/unenv-preset'

// Use with unenv

export default {

preset: preset

}

Features

Node.js Polyfills

This preset provides polyfills for common Node.js APIs to ensure compatibility when running code in the Azion Runtime environment. The following modules are polyfilled:

Module	Description
`crypto`	Complete cryptographic functionality including hashing, encryption, and UUID generation.
`events`	Event handling through `events/events.js`.
`http`	HTTP client functionality via `stream-http`.
`module`	Basic module system compatibility (limited functionality).
`stream`	Stream implementations via `stream-browserify`.
`string_decoder`	String decoding utilities.
`url`	URL parsing and formatting.
`util`	Utility functions.
`timers`	Timer functions via `timers-browserify`.
`vm`	Virtual Machine functionality via `vm-browserify`.
`zlib`	Compression functionality via `browserify-zlib`.

Example:

This exemple is using the crypto polyfill.

import { createHash, randomUUID } from 'azion/unenv-preset/polyfills/node/crypto'

// Create a hash

const hash = createHash('sha256')

hash.update('some data')

console.log(hash.digest('hex'))

// Generate a UUID

const uuid = randomUUID()

File System Polyfills

The preset includes comprehensive file system polyfills that mirror Node.js’s fs module functionality. These polyfills work with an in-memory file system when running in the Edge Runtime.

Basic File Operations

import { readFileSync, writeFileSync } from 'azion/unenv-preset/polyfills/node/fs'

// Read a file

const content = readFileSync('/path/to/file.txt', 'utf8')

// Write to a file

writeFileSync('/path/to/new-file.txt', 'Hello World', 'utf8')

Directory Operations

import { readdirSync, mkdirSync } from 'azion/unenv-preset/polyfills/node/fs'

// List directory contents

const files = readdirSync('/path/to/dir')

// Create a directory

mkdirSync('/path/to/new-dir')

File Stats and Information

import { statSync, existsSync } from 'azion/unenv-preset/polyfills/node/fs'

// Check if file exists

if (existsSync('/path/to/file.txt')) {

// Get file stats

const stats = statSync('/path/to/file.txt')

console.log(`File size: ${stats.size}`)

console.log(`Is directory: ${stats.isDirectory()}`)

console.log(`Is file: ${stats.isFile()}`)

}

File Descriptors

import { openSync, closeSync, readSync } from 'azion/unenv-preset/polyfills/node/fs'

// Open file and get file descriptor

const fd = openSync('/path/to/file.txt', 'r')

// Read from file descriptor

const buffer = Buffer.alloc(1024)

readSync(fd, buffer, 0, 1024, 0)

// Close file descriptor

closeSync(fd)

Global Polyfills

The preset also provides polyfills for Node.js global variables and objects:

Global Object	Description
`__dirname`	Current directory name.
`__filename`	Current file name.
`process`	Process information and environment (including env variables).
`performance`	Performance timing functionality.
`navigator`	Browser-compatible navigator object.

The preset also handles injection of these globals through the unenv configuration:

import { preset } from 'azion/unenv-preset'

// Preset configuration automatically injects globals

export default {

inject: {

__dirname: preset.inject.__dirname,

__filename: preset.inject.__filename,

process: preset.inject.process,

performance: preset.inject.performance,

navigator: preset.inject.navigator

}

API Reference

getFileContent

Decodes file content and returns it as either a Buffer or string.

Parameters:

Parameter	Description	Values
`file`	The file object containing content in base64 format.	—
`returnBuffer`	Determines return type (default: `true`).	`true` → Returns a Buffer,`false` → Returns a string.

Returns:

Return Type	Description
`Buffer \| string`	The decoded file content.

Example:

const fileBuffer = getFileContent(file) // returns Buffer

const fileString = getFileContent(file, false) // returns string

closeSync

Synchronously closes the file descriptor.

Parameters:

Parameter	Description
`fd`	The file descriptor to close.

Example:

closeSync(fd)

openSync

Synchronously opens a file.

Parameters:

Parameter	Description
`path`	The path to the file.
`flags`	The opening mode (for example, ‘r’, ‘w’).
`mode`	(Optional) The file mode.

Returns:

Return Type	Description
`number`	The file descriptor.

Example:

const fd = openSync('/path/to/file.txt', 'r')

statSync

Synchronously retrieves the fs.Stats for the specified path.

Parameters:

Parameter	Description
`path`	The path to the file or directory.
`options`	(Optional) Options for the stat call.

Returns:

Return Type	Description
`fs.Stats`	The stats object for the file or directory.

Example:

const stats = statSync('/path/to/file.txt')

readFileSync

Synchronously reads the entire contents of a file.

Parameters:

Parameter	Description
`path`	The file path.
`options`	(Optional) Options for reading the file.

Returns:

Return Type	Description
`string \| Buffer`	The file contents.

Example:

const content = readFileSync('/path/to/file.txt', 'utf8')

readdirSync

Synchronously reads the contents of a directory.

Parameters:

Parameter	Description
`path`	The directory path.
`options`	(Optional) Options for reading the directory.

Returns:

Return Type	Description
`string[]`	An array of file names in the directory.

Example:

const files = readdirSync('/path/to/dir')