Project: syntax-tree/unist-util-visit-parents

Package: unist-util-visit-parents@3.1.0

  1. Dependencies: 2·Dependents: 86
  2. unist utility to recursively walk over nodes, with ancestral information
  1. util 118
  2. utility 114
  3. unist 110
  4. tree 42
  5. ast 29
  6. unist-util 24
  7. check 11
  8. walk 7
  9. visit 5
  10. parent 2
  11. parents 2


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unist utility to visit nodes, with ancestral information.



npm install unist-util-visit-parents


var remark = require('remark')
var visit = require('unist-util-visit-parents')

var tree = remark.parse('Some _emphasis_, **importance**, and `code`.')

visit(tree, 'strong', visitor)

function visitor(node, ancestors) {


[ { type: 'root', children: [ [Object] ] },
  { type: 'paragraph',
     [ [Object],
       [Object] ] } ]


visit(tree[, test], visitor[, reverse])

Visit nodes (inclusive descendants of tree), with ancestral information. Optionally filtering nodes. Optionally in reverse.

This algorithm performs depth-first tree traversal in preorder (NLR), or if reverse is given, in reverse preorder (NRL).

Walking the tree is an intensive task. Make use of the return values of the visitor when possible. Instead of walking a tree multiple times with different tests, walk it once without a test, and use unist-util-is to check if a node matches a test, and then perform different operations.


next? = visitor(node, ancestors)

Invoked when a node (matching test, if given) is found.

Visitors are free to transform node. They can also transform the parent of node (the last of ancestors). Replacing node itself, if visit.SKIP is not returned, still causes its descendants to be visited. If adding or removing previous siblings (or next siblings, in case of reverse) of node, visitor should return a new index (number) to specify the sibling to traverse after node is traversed. Adding or removing next siblings of node (or previous siblings, in case of reverse) is handled as expected without needing to return a new index. Removing the children property of an ancestor still results in them being traversed.


The return value can have the following forms:


An action can have the following values:


index (number) — Move to the sibling at index next (after node itself is completely traversed). Useful if mutating the tree, such as removing the node the visitor is currently on, or any of its previous siblings (or next siblings, in case of reverse) Results less than 0 or greater than or equal to children.length stop traversing the parent


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 © Titus Wormer