unist-util-visit-parents
unist utility to visit nodes, with ancestral information.
Install
npm:
npm install unist-util-visit-parents
Usage
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) {
console.log(ancestors)
}
Yields:
[ { type: 'root', children: [ [Object] ] },
{ type: 'paragraph',
children:
[ [Object],
[Object],
[Object],
[Object],
[Object],
[Object],
[Object] ] } ]
API
visit(tree[, test], visitor[, reverse])
Visit nodes (inclusive descendants of tree
), with
ancestral information. Optionally filtering nodes. Optionally in reverse.
Parameters
tree
(Node
) — Tree to traversetest
(Test
, optional) — is
-compatible test (such as a
type)visitor
(Function) — Function invoked when a node is found
that passes test
reverse
(boolean
, default: false
) — The tree is walked in preorder
(NLR), visiting the node itself, then its head, etc.
When reverse
is passed, the tree is stilled walked in preorder, but now
in NRL (the node itself, then its tail, etc.)
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 parent still results in them being
traversed.
Parameters
node
(Node
) — Found nodeancestors
(Array.<Node>
) — Ancestors of node
Returns
The return value can have the following forms:
index
(number
) — Treated as a tuple of [CONTINUE, index]
action
(*
) — Treated as a tuple of [action]
tuple
(Array.<*>
) — List with one or two values, the first an action
,
the second and index
.
Note that passing a tuple only makes sense if the action
is SKIP
.
If the action
is EXIT
, that action can be returned.
If the action
is CONTINUE
, index
can be returned.
action
An action can have the following values:
visit.EXIT
(false
) — Stop traversing immediatelyvisit.CONTINUE
(true
) — Continue traversing as normal (same behaviour
as not returning anything)visit.SKIP
('skip'
) — Do not traverse this node’s children; continue
with the specified index
index
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
Related
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, organisation, or community you agree to
abide by its terms.
License
MIT © Titus Wormer