Project: syntax-tree/unist-builder

Package: unist-builder@3.0.0

  1. Dependents: 0
  2. unist utility to create a new trees with a nice syntax
  1. util 147
  2. utility 143
  3. unist 129
  4. tree 37
  5. ast 35
  6. unist-util 25
  7. syntax 21
  8. hyperscript 5
  9. dsl 4
  10. build 3


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unist utility to create trees with ease.


What is this?

This package is a hyperscript interface (like createElement from React and h from Vue and such) to help with creating unist trees.

When should I use this?

You can use this utility in your project when you generate syntax trees with code. It helps because it replaces most of the repetition otherwise needed in a syntax tree with function calls.

You can instead use hastscript or xastscript when creating hast (HTML) or xast (XML) nodes.


This package is ESM only. In Node.js (version 14.14+ and 16.0+), install with npm:

npm install unist-builder

In Deno with esm.sh:

import {u} from 'https://esm.sh/unist-builder@3'

In browsers with esm.sh:

<script type="module">
  import {u} from 'https://esm.sh/unist-builder@3?bundle'


import {u} from 'unist-builder'

const tree = u('root', [
  u('subtree', {id: 1}),
  u('subtree', {id: 2}, [
    u('node', [u('leaf', 'leaf 1'), u('leaf', 'leaf 2')]),
    u('leaf', {id: 3}, 'leaf 3'),
    u('void', {id: 4})

console.dir(tree, {depth: null})

results in the following tree:

  type: 'root',
  children: [
    {type: 'subtree', id: 1},
      type: 'subtree',
      id: 2,
      children: [
          type: 'node',
          children: [
            {type: 'leaf', value: 'leaf 1'},
            {type: 'leaf', value: 'leaf 2'}
        {type: 'leaf', id: 3, value: 'leaf 3'},
        {type: 'void', id: 4}


This package exports the identifier u. There is no default export.

u(type[, props][, children|value])

Build a node.


Built node (Node).


List to use as children or value to use as value (TypeScript type).

type ChildrenOrValue = Array<Node> | string


Other fields to add to the node (TypeScript type).

export type Props = Record<string, unknown>


This package is fully typed with TypeScript. It exports the additional types ChildrenOrValue and Props.


Projects maintained by the unified collective are compatible with all maintained versions of Node.js. As of now, that is Node.js 14.14+ and 16.0+. Our projects sometimes work with older versions, but this is not guaranteed.


See contributing.md in syntax-tree/.github for ways to get started. See support.md for ways to get help.

This project has a code of conduct. By interacting with this repository, organization, or community you agree to abide by its terms.


MIT © Eugene Sharygin