@electron/asar

Install the @electron/asar package using npm. This module requires Node.js version 22.12.0 or later.

npm install --engine-strict @electron/asar

Use createPackage to create an asar archive from a source directory.

Note: There is currently no error handling provided for this function.

import { createPackage } from '@electron/asar';

const src = 'some/path/';
const dest = 'name.asar';

await createPackage(src, dest);
console.log('done.');

Use createPackageWithOptions to apply a transformation to files as they are being packed into the .asar archive. The transform option accepts a function that returns either undefined or a stream.Transform instance. The transform stream will be applied to the files being written to the archive (useful for tasks like compression).

import { createPackageWithOptions } from '@electron/asar';

const src = 'some/path/';
const dest = 'name.asar';

function transform (filename) {
  return new CustomTransformStream()
}

await createPackageWithOptions(src, dest, { transform: transform });
console.log('done.');

When using the pack command, you can use the --unpack-dir option to exclude specific files or patterns from being packed into the archive (they will remain uncompressed/unpacked).

Examples:

• Exclude specific files: asar pack app app.asar --unpack-dir "{x1,x2}"
• Exclude using glob patterns: asar pack app app.asar --unpack-dir "**/{x1,x2}"
• Exclude complex patterns: asar pack app app.asar --unpack-dir "{**/x1,**/x2,z4/w1}"

Use getFileIntegrity to calculate the SHA256 hash and block-level hashes for a file provided as a NodeJS.ReadableStream. This is useful for verifying the integrity of files within an ASAR archive.

Returns a FileIntegrity object containing:

• algorithm: Always 'SHA256'.
• hash: The full file SHA256 hash in hex.
• blockSize: The size of each block used (default is 4MB).
• blocks: An array of hex-encoded SHA256 hashes for each block.

Use insertFile to add a file to the archive. This method requires a streamGenerator function that returns a NodeJS.ReadableStream of the file content.

Key constraints and behaviors:

• File Size Limit: Files cannot be larger than 4.2GB (UINT32_MAX).
• Unpacked Files: If shouldUnpack is true or the parent directory is marked as unpacked, the file is treated as an unpacked entry.
• Transformations: You can provide an optional transform function in the options object. If provided, the file is piped through the transform stream and the resulting bytes are what get stored and hashed in the archive.
• Integrity: The method automatically computes the file's integrity hash.