JsPack.ts

Library to pack/unpack binary data

JsPack is a library for working with binary data in JavaScript using the Uint8Array object. To ensure maximum stability, this library has 100% test coverage. The library was created using typescript for more convenient work with many types.

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Installation

Install with npm:

npm i jspack.ts

Formats

Key	Length	Type	Description	Examples
A	any	number[]	Array	Pack	Unpack
x	1	number	NUL-padded byte	Pack	Unpack
c	1	string	Single char (ascii)	Pack	Unpack
s	any	string	String char (ascii)	Pack	Unpack
b	1	number	Char (signed)	Pack	Unpack
B	1	number	Char (unsigned)	Pack	Unpack
h	2	number	Short (signed)	Pack	Unpack
H	2	number	Short (unsigned)	Pack	Unpack
i	4	number	Int (signed)	Pack	Unpack
I	4	number	Int (unsigned)	Pack	Unpack
l	4	number	Long (signed)	Pack	Unpack
L	4	number	Long (unsigned)	Pack	Unpack
q	8	number	Long long (signed)	Pack	Unpack
Q	8	number	Long long (unsigned)	Pack	Unpack
f	4	number¹	Float	Pack	Unpack
d	8	number¹	Double	Pack	Unpack

Superscripts:

1: Unpack with 'f' and 'd' key can return NaN. The value NAN is used to represent a value that is an error. This is represented when exponent field is all ones with a zero sign bit or a mantissa that it not 1 followed by zeros. This is a special value that might be used to denote a variable that doesn’t yet hold a value.

Endianness

Key	Description
<	Little endian
>	Big endian
!	Network (big endian)

Initialization

ES6:

import { JSPack, JSPackFormat, JSPackEndianness } from 'jspack.ts';

Node:

const { JSPack, JSPackFormat, JSPackEndianness } = require('jspack.ts');

Examples

Formats:

• Char (ascii)
• Int
• Int64 (long long int)
• String (ASCII chars)
• Array (Raw data)
• IEEE 754 (Float, Double)
• Null Byte

---

Char (ascii)

Pack:

// Return Uint8Array(97)
JSPack.Pack(JSPackFormat.c, 'a', JSPackEndianness.bigEndian);

Unpack:

// Return 'b'
JSPack.Unpack(JSPackFormat.c, new Uint8Array([98]), JSPackEndianness.bigEndian);

---

Int

Pack:

// Return Uint8Array(0x85)
JSPack.Pack(JSPackFormat.b, -123, JSPackEndianness.bigEndian);

Unpack:

// Return -123
JSPack.Unpack(JSPackFormat.b, new Uint8Array([0x85]), JSPackEndianness.bigEndian);

---

Int64 (long long int)

Pack:

// Return Uint8Array(0x00, 0x01, 0xEE, 0x0D, 0x32, 0xDE, 0xBC, 0xD1)
const longLongInt = {
    low: 0x32DEBCD1,
    high: 0x0001EE0D,
    unsigned: true,
};

JSPack.Pack(JSPackFormat.q, longLongInt, JSPackEndianness.bigEndian);

Unpack:

const longLongIntBinary = new Uint8Array([0x00, 0x01, 0xEE, 0x0D, 0x32, 0xDE, 0xBC, 0xD1]);

// Return { low: 0x32DEBCD1, high: 0x0001EE0D, unsigned: true }
JSPack.Unpack(JSPackFormat.q, longLongIntBinary, JSPackEndianness.bigEndian);

---

String (ASCII chars)

Pack:

// Return Uint8Array(97, 98, 99)
JSPack.Pack(JSPackFormat.s, 'abc', JSPackEndianness.bigEndian);

Unpack:

// Return 'abc'
JSPack.Unpack(JSPackFormat.s, new Uint8Array([97, 98, 99]), JSPackEndianness.bigEndian);

---

Array (Raw data)

Pack:

// Return Uint8Array(0x61, 0x62, 0x63)
JSPack.Pack(JSPackFormat.A, [97, 98, 99], JSPackEndianness.bigEndian);

Unpack:

// Return [97, 98, 99]
JSPack.Unpack(JSPackFormat.A, new Uint8Array([0x61, 0x62, 0x63]), JSPackEndianness.bigEndian);

---

IEEE 754 (Float, Double)

Pack:

// Return Uint8Array(0x47, 0x59, 0x3, 0x55)
JSPack.Pack(JSPackFormat.f, 55555.333, JSPackEndianness.bigEndian);

Unpack:

// Return 55555.33203125
JSPack.Unpack(JSPackFormat.f, new Uint8Array([0x47, 0x59, 0x3, 0x55]), JSPackEndianness.bigEndian);

---

Null Byte

Pack:

// Return Uint8Array(0)
JSPack.Pack(JSPackFormat.x, 0x0, JSPackEndianness.bigEndian);

Unpack:

// Return 0
JSPack.Unpack(JSPackFormat.x, new Uint8Array([0]), JSPackEndianness.bigEndian);