eznbt

Easy Minecraft NBT reading and writing

Prerequisites

Make sure to use a node version that supports BigInts, they're used for the Long NBT Tag

Usage

Pretty much all you need to know is that PascalCase members of eznbt are classes that can be used for both reading and writing. Its constructors accept an object containing either a value or buffer property, from which the class is then constructed. The instance will contain a value and buffer property.

For ease of use lowercase members of eznbt can be used to construct classes like this: int(5) (instead of new Int({ value: 5 }))

Writing stuff

import NBT from 'eznbt'
const { NBTString, string, rootcompound } = NBT
 
/* NBT files are usually implicitly in a compound. If this is the case you should use
 * a named RootCompound. You name it by providing a [Symbol.for('NBTRootTagName')] string.
 */
const myCompound = rootcompound({
  [Symbol.for('NBTRootTagName')]: 'rootTagName',
  myStr: new NBTString({ value: 'hello' }),
  // is equivalent to
  myStr2: new NBT.String({ value: 'hello' }),
  // is equivalent to
  myStr3: string('hello'),
  // is equivalent to
  myStr4: 'hello'
})
 
myCompound.buffer // ready to send to your client/server

Reading stuff

import NBT from 'eznbt'
const { Compound } = NBT
 
const myBuffer = ... // a buffer you received. it is an nbt compound tag (as always)
const myCompound = new Compound({ buffer: myBuffer })
myCompound.value // yields the compound as an object. children are NBT Tag instances
myCompound.json // yields the compound as an object. children are JS types (number, string, bigint, etc.)

Reading and writing lists

Lists are special because they have one set type, which you will first have to pass to the List or list function.

import NBT from 'eznbt'
const { List, list, NBTString } = NBT
 
 
const myList = list(NBTString)('hello', 'world!') // creates a string-list
 
// When the type of the list is unknown, it can only be used to read stuff:
const { value } = new (List())({ buffer: myList.buffer })

Compound shorthands

The compound tag comes with a few handy shorthands

import NBT from 'eznbt'
const { int, compound } = NBT
 
const myCompound = compound({
  myList: [int(5), int(6)], // creates an int-list
  myLong: 5n, // creates a long
  myStr: 'hello world!', // creates a string
  // creates a compound
  myCompound: {
    myLongList: [5n, 6n, 7n] // creates a long-list
  }
})

Compound vs RootCompound

Since generally all NBT files are implicitly in a compound tag, you should probably always use RootCompound for the outside object, and Compound otherwise

// RootCompound.json vs Compound.json
 
// RootCompound.json will put all values as a property of the root compound's name
rootcompound({ a: 1, b: 2, [Symbol.for('NBTRootTagName')]: 'hello!' }).json
/** {
  *   'hello!': {
  *     a: 1,
  *     b: 2
  *   }
  * }
  */
 
// Compound doesn't have a name so it won't be named
compound({ a: 1, b: 2 }).json
/** {
  *   a: 1,
  *   b: 2
  * }
  */

Typescript

This package has been made using Typescript and ships with type declarations.