unist-util-visit

unist utility to walk the tree.

Contents

• What is this?
• When should I use this?
• Install
• Use
• API
  • visit(tree[, test], enter|visitors[, reverse])
  • CONTINUE
  • EXIT
  • SKIP
  • Action
  • ActionTuple
  • BuildVisitor
  • BuildVisitors
  • Index
  • Test
  • Visitor
  • VisitorExit
  • VisitorResult
  • VisitorResultExit
  • Visitors
• Compatibility
• Related
• Contribute
• License

What is this?

This is a very important utility for working with unist as it lets you walk the tree.

When should I use this?

You can use this utility when you want to walk the tree. You can use unist-util-visit-parents if you care about the entire stack of parents.

Install

This package is ESM only. In Node.js (version 16+), install with npm:

npm install unist-util-visit

In Deno with esm.sh:

import {CONTINUE, EXIT, SKIP, visit} from 'https://esm.sh/unist-util-visit@5'

In browsers with esm.sh:

<script type="module">
  import {CONTINUE, EXIT, SKIP, visit} from 'https://esm.sh/unist-util-visit@5?bundle'
</script>

Use

import {fromMarkdown} from 'mdast-util-from-markdown'
import {visit} from 'unist-util-visit'

const tree = fromMarkdown('Some *emphasis*, **strong**, and `code`.')

visit(tree, 'text', function (node, index, parent) {
  console.log([node.value, parent ? parent.type : index])
})

Yields:

[ 'Some ', 'paragraph' ]
[ 'emphasis', 'emphasis' ]
[ ', ', 'paragraph' ]
[ 'strong', 'strong' ]
[ ', and ', 'paragraph' ]
[ '.', 'paragraph' ]

API

This package exports the identifiers CONTINUE, EXIT, SKIP, and visit. It exports the TypeScript types ActionTuple, Action, BuildVisitor, BuildVisitors, Index, Test, VisitorExit, VisitorResultExit, VisitorResult, Visitors, and Visitor. There is no default export.

visit(tree[, test], enter|visitors[, reverse])

This function works exactly the same as unist-util-visit-parents, but Visitor and VisitorExit have a different signature.

Signatures

• visit(tree[, test], enter[, reverse])
• visit(tree[, test], visitors[, reverse])

CONTINUE

Continue traversing as normal (true).

EXIT

Stop traversing immediately (false).

SKIP

Do not traverse this node’s children ('skip').

Action

Union of the action types (TypeScript type). See Action in unist-util-visit-parents.

ActionTuple

List with an action and an index (TypeScript type). See ActionTuple in unist-util-visit-parents.

BuildVisitor

Build a typed Visitor function from a tree and a test (TypeScript type). See BuildVisitor in unist-util-visit-parents.

BuildVisitors

Build typed Visitors from a tree and a test (TypeScript type). See BuildVisitors in unist-util-visit-parents.

Index

Move to the sibling at index next (TypeScript type). See Index in unist-util-visit-parents.

Test

unist-util-is compatible test (TypeScript type).

Visitor

Handle a node (matching test, if given) before its children (TypeScript type). Like Visitor in unist-util-visit-parents, but with index and parent instead of parents.

Parameters

• node (Node) — found node
• index (number or undefined) — index of node in parent, or undefined for the tree itself
• parent (Node or undefined) — parent of node, or undefined for the tree itself

Returns

What to do next (VisitorResult).

VisitorExit

Handle a node (matching test, if given) after its children (TypeScript type). Like VisitorExit in unist-util-visit-parents, but with index and parent instead of parents.

Parameters

• node (Node) — found node
• index (number or undefined) — index of node in parent, or undefined for the tree itself
• parent (Node or undefined) — parent of node, or undefined for the tree itself

Returns

What to do next (VisitorResultExit).

VisitorResult

Any value that can be returned from a visitor (TypeScript type). See VisitorResult in unist-util-visit-parents.

VisitorResultExit

Any value that can be returned from an exit visitor (TypeScript type). See VisitorResultExit in unist-util-visit-parents.

Visitors

Handle nodes when entering and exiting them (TypeScript type). See Visitors in unist-util-visit-parents.

Fields

• enter (Visitor, optional) — handle a node before its children
• exit (VisitorExit) — handle a node after its children

Compatibility

Projects maintained by the unified collective are compatible with maintained versions of Node.js.

When we cut a new major release, we drop support for unmaintained versions of Node. This means we try to keep the current release line, unist-util-visit@^5, compatible with Node.js 16.

Related

• unist-util-visit-parents — walk the tree with a stack of parents
• unist-util-filter — create a new tree with all nodes that pass a test
• unist-util-map — create a new tree with all nodes mapped by a given function
• unist-util-flatmap — create a new tree by mapping (to an array) with the given function
• unist-util-remove — remove nodes from a tree that pass a test
• unist-util-select — select nodes with CSS-like selectors

Contribute

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.

License

MIT © Titus Wormer