README.md

UNIST UTIL WALKER

Talk the Talk - Walk the Tree

Inspired by estree-walker, this package provides a method to walk unist trees, by providing an enter and leave function. The main advantage over unist-util-visit is that we can enter all child nodes and accumulate data, which we can then use in the leave function of the parent.

Installation

This package is ESM only: Node 12+ is needed to use it and it must be imported instead of required.

NPM

npm install unist-util-walker

YARN

yarn add unist-util-walker

PNPM

pnpm add unist-util-walker

Usage

import type { Node, Parent } from 'unist';
import { walk } from 'unist-util-walker';
import { u } from 'unist-builder';

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

walk(tree, {
  enter(node: Node, parent?: Parent, index?: number) {
    // some code happens
  },
  leave(node: Node, parent?: Parent, index?: number) {
    // some code happens
  }
});

Inside of the enter and leave functions, you can call the following functions:

• this.break()
  Skips children and the leave function of the current node (only useful in enter).
• this.skip()
  Skips children, but still runs the leave function of the current node (only useful in enter).
• this.remove()
  Removes the node from the tree (has no effect on root node).
• this.replace(node: Node)
  Replaces the node with a new one.