oo-ascii-tree

oo-ascii-tree

Renders ASCII trees from an object-oriented object graph.

Features:

• Multiline text
• Multiple root nodes

Roadmap:

• Customization of tree formatting and indentation size

Install

$ npm i oo-ascii-tree

Basic Example

import { AsciiTree } from '../lib';

const tree = new AsciiTree('root');

tree.add(new AsciiTree('child1'));

tree.add(new AsciiTree('child2',
  new AsciiTree('grandchild1'),
  new AsciiTree('grandchild2')
));

tree.add(new AsciiTree('child3'));

tree.printTree();

Prints the following tree to stdout:

root
 ├── child1
 ├─┬ child2
 │ ├── grandchild1
 │ └── grandchild2
 └── child3

Advanced Usage

You can also subclass AsciiTree to encapsulate some model. The following example declares a TitleNode which formats a title with "====" underline and a KeyValueNode which formats text as key: value:

class TitleNode extends AsciiTree {
  constructor(title: string, ...children: AsciiTree[]) {
    super([
      title.toLocaleUpperCase(),
      '='.repeat(title.length)
    ].join('\n'), ...children);
  }
}

class KeyValueNode extends AsciiTree {
  constructor(key: string, value: string) {
    super(`${key}: ${value}`);
  }
}

const tree = new AsciiTree();

tree.add(new TitleNode('props',
  new KeyValueNode('shape', 'circle'),
  new KeyValueNode('color', 'red'),
  new KeyValueNode('background', 'blue')
));

tree.add(new TitleNode('dimensions',
  new KeyValueNode('width', '30px'),
  new KeyValueNode('height', '40px')
));

Will emit the following output:

PROPS
=====
 ├── shape: circle
 ├── color: red
 └── background: blue
DIMENSIONS
==========
 ├── width: 30px
 └── height: 40px

API

The AsciiTree class represents a tree/node/subtree. Each node in the tree includes text and children and can be printed to a Writable via printTree(stream).

new AsciiTree([text[, children...]])

Creates a new node with the specified text and optionally adds child nodes to it.

If text is not specified, the children of this node will all be considered roots (level 0) and the root node will get level -1. This allows modeling trees with a single root or with multiple roots.

asciiTree.add(children...)

Adds one or more children to the node.

asciiTree.printTree([writableStream])

Emits an ASCII print out of the tree to the specified Writable stream. The default is process.stdout.

asciiTree.toString()

Returns a string representation of the tree.

asciiTree.text

The node's text. If the text contains multiple line separated by \n, new lines will be aligned to the node's indentation.

asciiTree.children

Returns a copy of the array of children of this node. Use asciiTree.add to add children.

asciiTree.root

Returns true if this is the root node.

asciiTree.last

Returns true if this is the last child of a node.

asciiTree.level

Returns the node level. Root node(s) will have a level of 0.

If the root AsciiTree has text, it's level will be 0 and its children will get level 1. If the root AsciiTree does not have text, it's level will be -1 and all it's children will get level 0.

asciiTree.empty

Returns true if this node does not have any children.

asciiTree.ancestors

Returns all the nodes that are ancestors of this node ordered from root to the direct parent.

License

Distributed under the Apache License, Version 2.0.

See LICENSE and NOTICE for more information.

Changelog

1.114.1 (2025-09-04)

Features

• jsii and jsii-rosetta v5.9 (#4885) (fd4385a)
• prepare support for intersection types (#4898) (d75658e)