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unist utility to check if nodes pass a test.

• What is this?
• When should I use this?
• Install
• Use
• API
  • is(node[, test[, index, parent[, context]]])
  • convert(test)
  • Check
  • Test
  • TestFunction
• Examples
  • Example ofconvert
• Types
• Compatibility
• Related
• Contribute
• License

This package is a small utility that checks that a node is a certain node.

Use this small utility if you find yourself repeating code for checking whatnodes are.

A similar package,hast-util-is-element, works on hastelements.

For more advanced tests,unist-util-select can be usedto match against CSS selectors.

This package isESM only.In Node.js (version 16+), install withnpm:

npm install unist-util-is

In Deno withesm.sh:

import{is}from'https://esm.sh/unist-util-is@6'

In browsers withesm.sh:

<scripttype="module">import{is}from'https://esm.sh/unist-util-is@6?bundle'</script>

import{is}from'unist-util-is'constnode={type:'strong'}constparent={type:'paragraph',children:[node]}is()// => falseis({children:[]})// => falseis(node)// => trueis(node,'strong')// => trueis(node,'emphasis')// => falseis(node,node)// => trueis(parent,{type:'paragraph'})// => trueis(parent,{type:'strong'})// => falseis(node,test)// => falseis(node,test,4,parent)// => falseis(node,test,5,parent)// => truefunctiontest(node,n){returnn===5}

This package exports the identifiersconvert andis.There is no default export.

Check ifnode is aNode and whether it passes the given test.

• node (unknown, optional)— thing to check, typicallyNode
• test (Test, optional)— a test for a specific element
• index (number, optional)— the node’s position in its parent
• parent (Node, optional)— the node’s parent
• context (unknown, optional)— context object (this) to calltest with

Whethernode is aNode and passes a test (boolean).

When an incorrecttest,index, orparent is given.There is no error thrown whennode is not a node.

Generate a check from a test.

Useful if you’re going to test many nodes, for example when creating autility where something else passes a compatible test.

The created function is a bit faster because it expects valid input only:anode,index, andparent.

• test (Test, optional)— a test for a specific node

A check (Check).

Check that an arbitrary value is a node (TypeScript type).

• this (unknown, optional)— context object (this) to calltest with
• node (unknown)— anything (typically a node)
• index (number, optional)— the node’s position in its parent
• parent (Node, optional)— the node’s parent

Whether this is a node and passes a test (boolean).

Check for an arbitrary node (TypeScript type).

typeTest=|Array<Record<string,unknown>|TestFunction|string>|Record<string,unknown>|TestFunction|string|null|undefined

Checks that the given thing is a node, and then:

• whenstring, checks that the node has that tag name
• whenfunction, seeTestFunction
• whenobject, checks that all keys in test are in node, and that they have(strictly) equal values
• whenArray, checks if one of the subtests pass

Check if a node passes a test (TypeScript type).

• node (Node)— a node
• index (number orundefined)— the node’s position in its parent
• parent (Node orundefined)— the node’s parent

Whether this node passes the test (boolean, optional).

import{u}from'unist-builder'import{convert}from'unist-util-is'consttest=convert('leaf')consttree=u('tree',[u('node',[u('leaf','1')]),u('leaf','2'),u('node',[u('leaf','3'),u('leaf','4')]),u('leaf','5')])constleafs=tree.children.filter(function(child,index){returntest(child,index,tree)})console.log(leafs)

Yields:

[{type:'leaf',value:'2'},{type:'leaf',value:'5'}]

This package is fully typed withTypeScript.It exports the additional typesCheck,Test,TestFunction.

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

When we cut a new major release, we drop support for unmaintained versions ofNode.This means we try to keep the current release line,unist-util-is@^6,compatible with Node.js 16.

• unist-util-find-after— find a node after another node
• unist-util-find-before— find a node before another node
• unist-util-find-all-after— find all nodes after another node
• unist-util-find-all-before— find all nodes before another node
• unist-util-find-all-between— find all nodes between two nodes
• unist-util-filter— create a new tree with nodes that pass a check
• unist-util-remove— remove nodes from tree

Seecontributing.md insyntax-tree/.github forways to get started.Seesupport.md for ways to get help.

This project has acode of conduct.By interacting with this repository, organization, or community you agree toabide by its terms.

MIT ©Titus Wormer