unist utility to walk the tree.

• What is this?
• When should I use this?
• Install
• Use
• API
  • visit(tree[, test], visitor[, reverse])
  • CONTINUE
  • EXIT
  • SKIP
  • Action
  • ActionTuple
  • BuildVisitor
  • Index
  • Test
  • Visitor
  • VisitorResult
• Types
• Compatibility
• Related
• Contribute
• License

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

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.

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>

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' ]

This package exports the identifiers CONTINUE, EXIT, SKIP, and visit. There is no default export.

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

Continue traversing as normal (true).

Stop traversing immediately (false).

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

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

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

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

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

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

Handle a node (matching test, if given) (TypeScript type).

Visitors are free to transform node. They can also transform parent.

Replacing node itself, if SKIP is not returned, still causes its descendants to be walked (which is a bug).

When adding or removing previous siblings of node (or next siblings, in case of reverse), the Visitor should return a new Index 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 parent still results in them being traversed.

• node (Node) — found node
• index (number or undefined) — index of node in parent
• parent (Node or undefined) — parent of node

What to do next.

An Index is treated as a tuple of [CONTINUE, Index]. An Action is treated as a tuple of [Action].

Passing a tuple back only makes sense if the Action is SKIP. When the Action is EXIT, that action can be returned. When the Action is CONTINUE, Index can be returned.

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

This package is fully typed with TypeScript. It exports the additional types Action, ActionTuple, BuildVisitor, Index, Test, Visitor, and VisitorResult.

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.

• 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

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