nbt-ts

⚠️ This library has not been maintained for some time. Please use it with caution or switch to another implementation!

An easy to use encoder and decoder for the NBT format.

NBT compound tags are represented as plain JavaScript objects. The Byte, Short, Int and Float number types are wrapped in custom classes since JavaScript does not support them directly.

Node 10.4 or higher is required for BigInts, which are used to represent 64 bit integers.

Usage

const { encode, decode, Byte, Short, Int, Float } = require("nbt-ts")

const buffer = encode("root", {
    byte: new Byte(-1),
    short: new Short(65535),
    int: new Int(-2147483648),
    long: 0x7fffffffffffffffn,
    float: new Float(0.75),
    double: 0.1 + 0.2,
    string: "Hello world",
    list: ["item 1", "item 2"],
    compound: {
        byteArray: Buffer.from([0x80, 0x40, 0x20]),
        // Int8Array does work here too
        intArray: new Int32Array([1, 2, 3, 4]),
        longArray: new BigInt64Array([1n, 2n, 3n, 4n])
    },
})

decode(Buffer.from("02000973686F7274546573747FFF", "hex"))
// → { name: 'shortTest', value: Short { value: 32767 }, length: 14 }

// Encode unnamed tag
encode(null, "a")
// → <Buffer 08 00 01 61>

// Decode unnamed tag
decode(Buffer.from("08000161", "hex"), { unnamed: true })
// → { name: null, value: 'a', length: 4 }

Note that the encode function accepts both unsigned numbers such as 255 and signed numbers like -1 which are essentially the same in the case of a 8 bit integer. However when decoded, they will always have the signed representation. If you want to convert a number to the unsigned representation, you might do something like this:

value & 0xff   // for bytes
value & 0xffff // for shorts
value >>> 0    // for ints
BigInt.asUintN(64, value) // for longs
// or
value & 0xffffffffffffffffn

SNBT

The NBT format also has a more user-friendly variant in plain text. This format is referred to as SNBT, short for stringified NBT. Here are all the types represented in SNBT:

{
    byte: 1b, short: 1s, int: 1, long: 1l,
    float: 0.5f, double: 0.5,
    string: "Hello world",
    list: [{}, {}],
    compound: {
        byteArray: [B; 128, 64, 32],
        intArray: [I; 1, 2, 3, 4],
        longArray: [L; 1, 2, 3, 4]
    }
}

Here is an example how you can stringify or parse SNBT:

const { stringify, parse } = require("nbt-ts")

const tag = parse(`{'Flying' :1b , unquoted: hello} `)
// → { Flying: Byte { value: 1 }, unquoted: 'hello' }

stringify(tag)
// → '{Flying:1b,unquoted:"hello"}'

Related projects

• mc-chat-format. Converts and formats Minecraft's JSON Chat components.
• mcproto (Minecraft protocol implementation)
• rcon-client

Changelog

All notable changes to this library will be documented here.

1.2.5

• Fixed bug with encoding and decoding null tags.

1.2.1

• Fixed a few bugs with SNBT parsing and serialization.

1.2.0

• Added support for stringified NBT tags.

1.1.0

• Added support for Int8Arrays in encode function.
• Switched to using node's buffer bigint methods with temporary shim until node 12 reaches active LTS stage.

1.0.5

• Fixed bug with dataview in array conversion.

1.0.4

• Added basic tests for encoding and decoding.

1.0.0

• First major release since the API is mostly stable.
• Allow null as tag value in encode function.

0.1.2

• Added support for int arrays and long arrays.

0.1.0

• Initial release