json-arraybuffer-reviver/dist/main/index.js

Utility functions for JSON.parse and JSON.stringify to work with typed arrays and array buffers.

'use strict';

Object.defineProperty(exports, '__esModule', { value: true });

var libauth = require('@bitauth/libauth');

// Import binToHex and hexToBin utility functions from libauth.

// Define a list of supported view types.
/** @type {{ [index: string]: any }} */
const dataViews =
{
	Int8Array,
	Int16Array,
	Int32Array,

	Uint8Array,
	Uint16Array,
	Uint32Array,

	Uint8ClampedArray,

	Float32Array,
	Float64Array,
};

// Add the BigInt arrays if supported on the current platform.
if(typeof BigInt64Array !== 'undefined')
{
	dataViews.BigInt64Array = BigInt64Array;
	dataViews.BigUint64Array = BigUint64Array;
}

/**
 * Utility function to be used with JSON.stringify in order to encode ArrayBuffers and their data.
 *
 * @param key     {any}   the key/index of the data to replace.
 * @param value   {any}   the value of the data to replace.new Uint8Array(
 *
 * @returns {any}
 */
const replacer = function(key, value)
{
	// If the value if a big integer..
	if(typeof value === 'bigint')
	{
		// Return a replacement object, encoding the number as a string.
		return { $BigInt: value.toString() };
	}

	// If the value is a typed array buffer..
	if(ArrayBuffer.isView(value))
	{
		// Create an replacement object, encoding the data as a hex string.
		const replacement =
		{
			$ArrayBuffer:
			{
				View: value.constructor.name,
				Data: libauth.binToHex(new Uint8Array(value.buffer)),
			},
		};

		// Return the replacement.
		return replacement;
	}

	// If the value is non-typed array buffer..
	if(value instanceof ArrayBuffer)
	{
		// Create an replacement object, encoding the data as a hex string.
		const replacement =
		{
			$ArrayBuffer:
			{
				View: value.constructor.name,
				Data: libauth.binToHex(new Uint8Array(value)),
			},
		};

		// Return the replacement.
		return replacement;
	}

	// The value is not a typed array, so return the original value.
	return value;
};

/**
 * Utility function to be used with JSON.parse in order to decode ArrayBuffers and their data.
 *
 * @param key     {any}   the key/index of the data to restore.
 * @param value   {any}   the value of the data to restore.
 *
 * @returns {any}
 */
const reviver = function(key, value)
{
	// If the data is a big integer, encoded as a string..
	if(value.$BigInt)
	{
		// Return the number as a big integer.
		return BigInt(value.$BigInt);
	}

	// If the data is an array buffer..
	if(value.$ArrayBuffer)
	{
		// If it lacks a data view..
		if(value.$ArrayBuffer.View === 'ArrayBuffer')
		{
			// Return the buffer containing the data.
			return libauth.hexToBin(value.$ArrayBuffer.Data).buffer;
		}

		// Since it has a type view, return the corresponding view of the data.
		return new dataViews[value.$ArrayBuffer.View](libauth.hexToBin(value.$ArrayBuffer.Data).buffer);
	}

	// The value is not a typed array, so return the original value.
	return value;
};

exports.replacer = replacer;
exports.reviver = reviver;