Add countChildren

packages/docs/src/api.md

@@ -60,6 +60,27 @@ The passed array and its contents will be left unmodified. Any fragment nodes wi
 * [Example - Inserting between children](/examples.html#inserting-between-children)
 * [Guide - Inserting new nodes](/guide/inserting-new-nodes.html)
 
+## countChildren() <Badge text="0.3+" />
+
+### Type
+
+```ts
+function countChildren(
+  children: VNodeArrayChildren,
+  options: IterationOptions = ALL_VNODES
+): number
+```
+
+### Description
+
+Counts the number of 'top-level' VNodes. The children of a fragment will be considered 'top-level' nodes rather than the fragment itself.
+
+The [`options`](#iterationoptions) object can be used to decide which node types should be counted. If no options object is passed then all nodes will be counted. If an `options` object is passed, all nodes will be skipped by default unless explicitly ruled in.
+
+### See also
+
+* [Guide - Other helpers](/guide/other-helpers.html)
+
 ## eachChild()
 
 ### Type

packages/docs/src/guide/iterators.md

@@ -86,7 +86,8 @@ export default function ChildComponent(_, { slots }) {
 
 See it on the SFC Playground: [Composition API](https://play.vuejs.org/#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) | [Options API](https://play.vuejs.org/#eNp9Vftv0zAQ/ldOAamdaJPykJDCxoBp4v0Qm8QPBEEWO42pa0f2pSuq+r9zfiRry4Y2qfXdd9/d+e5zN8nLtk1XHU/y5NhWRrT4vFBi2WqD8EFY/CawudRYSqiNXsIozfas6W87KhRAofjaxzBel51E2DhrpYlIcYU2DwbY53Sm7STEA7ASy/FRDzQcO6P6E4BAviSa7/0ZYAPI15jD6CtnownYRl/ngKbjkfMA9dpwrgZcXUp7B/CV7PgBX4/6Eb74s4t1n0uOjWY3Hbq4l1L2nRRYYK0NjCutLPo2QNeAjbCp72nouO8ydQxw4lP3nlhBSFwo+j/OhnHRgcJaWSKnE8DxVYeoFbyopKgWJ0USSyoS7wa4cAlKMjhwFtAhUtJ4ptc0nym6AUX8QA+rKfVCjL4NocJUBl5PQBhRR4hvZcdNt7wJPbq7hu1wsbcUvXsVflrE80Ywvlewj8yk6AvN9i+CPIf97EGSSRJ2fbosW9plrUgHYWzRQc0Nky2SF3YhDEqekWKmK6UZn3YopAcVSYPY2jzLOtUu5iktf3YXPmNU16Ex5XY5vTL62nKTMr6ieoqkHzhVeig8KjUKdQMNbKNAiZQUOTgMZ13FzxohmeFqAhfv3375efb548fzT5cXQ9BddRLTP8quO1WhoEl50rNe4uOfE0pnpUYL27jTYeWrmJzm6N3Um2c6TUkjp6fw3atqB687hQTeL33c05AyuyWcPPcfD+DhBGYHbR31fPENacYjJlYk6fh4DOdfnjwkzOH+xn/Z/jqKr0Io5NThO0nwvoIjyEF1QT4/KBnNh8Zj8Y/kNq2sG0xc5gdAicJdXGnDuMnhYbsGq6VgcG82mz3zL0hp5kLRhrbknrXraFzT4jJscng0641tyZhQ8wFGmQuqJGYoq8XcUM0sh3v1U/fng27JXFXVTuZABzNw5XhKUrGn3MsX3NQpWhpULeYHgnGvvZDcfG7deuwLhx4bff3O29yzFi+YYhpeLW6x/7broKkvhpMcViT+wYdUNMfgPr/4RA/JjnOpWScJ/R/nV063QOutVYC9ohujsndwvtq3XkLU/aU9XyNXtm+qf5fjL1dCmnEquKv1m3Ifp08GOW//AlHHcjQ=)
 
+For the specific case of counting children, the dedicated [`countChildren()`](./other-helpers#counting-children) helper could be used instead.
 
-While these examples need to display the count, a more common scenario involves only needing to know whether the count is 0. The [`isEmpty()`](/api.html#isempty) helper can be used in that case.
+While these examples need to display the count, a more common scenario involves only needing to know whether the count is 0. The [`isEmpty()`](./other-helpers#checking-for-an-empty-slot) helper can be used in that case.
 
 It is worth noting that the count here is just a count of the VNodes. It is not necessarily an accurate count of the number of `<li>` elements. If any of the children had been a component it would have added 1 to the count, even though a component wouldn't necessarily render exactly one `<li>` element.

packages/docs/src/guide/other-helpers.md

@@ -1,5 +1,32 @@
 # Other helpers
 
+## Counting children
+
+A helper for counting the children.
+
+This uses the same iteration logic as the various [iterators](./iterators). Fragments are not counted directly, with the children of any fragments being counted instead.
+
+The second argument of `countChildren()` is optional and allows [iteration options](/api.html#iterationoptions) to be specified, controlling the types of VNodes that are counted.
+
+```js
+import { h } from 'vue'
+import { countChildren, SKIP_COMMENTS } from '@skirtle/vue-vnode-utils'
+
+function ChildComponent(_, { slots }) {
+  const children = slots.default?.() ?? []
+  const count = countChildren(children, SKIP_COMMENTS)
+
+  return h('div', [
+    h('div', `Child count: ${count}`),
+    count ? h('ul', children) : null
+  ])
+}
+```
+
+See it on the SFC Playground: [Composition API](https://play.vuejs.org/#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) | [Options API](https://play.vuejs.org/#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)
+
+If you need more fine-grained control over the counting you can use [`eachChild()` or `reduceChildren()`](./iterators) instead.
+
 ## Extracting a single child
 
 Slots return an array of children, but some components only allow for one child in their slot, like Vue's built-in components `<KeepAlive>` and `<Transition>`. `extractSingleChild()` can be used to pull out a meaningful root node from a slot. It skips over fragments, comments and text nodes, trying to find a component or element node.

packages/vue-vnode-utils/src/__tests__/iterators.spec.ts

@@ -28,6 +28,7 @@ import {
   ALL_VNODES,
   betweenChildren,
   COMPONENTS_AND_ELEMENTS,
+  countChildren,
   eachChild,
   everyChild,
   extractSingleChild,
@@ -1615,3 +1616,29 @@ describe('extractSingleChild', () => {
     expect(out).toBe(node)
   })
 })
+
+describe('countChildren', () => {
+  it('countChildren - 129c', () => {
+    expect(countChildren([])).toBe(0)
+    expect(countChildren([''])).toBe(1)
+    expect(countChildren(['Text'])).toBe(1)
+    expect(countChildren(['Text', 'Text'])).toBe(2)
+    expect(countChildren([['Text', 'Text', ['Text']], 'Text'])).toBe(4)
+    expect(countChildren([null])).toBe(1)
+    expect(countChildren([false])).toBe(1)
+    expect(countChildren([true])).toBe(1)
+    expect(countChildren([h('div')])).toBe(1)
+    expect(countChildren([h('div', {}, [h('span')])])).toBe(1)
+    expect(countChildren([h({ template: 'abc' })])).toBe(1)
+  })
+
+  it('countChildren - 9294', () => {
+    const children = [[], ['Text'], '', h('div'), h('span'), null, h({ template: 'abc' })]
+
+    expect(countChildren(children)).toBe(6)
+    expect(countChildren(children, ALL_VNODES)).toBe(6)
+    expect(countChildren(children, COMPONENTS_AND_ELEMENTS)).toBe(3)
+    expect(countChildren(children, SKIP_COMMENTS)).toBe(5)
+    expect(countChildren(children, {})).toBe(0)
+  })
+})

packages/vue-vnode-utils/src/index.ts

@@ -16,6 +16,7 @@ export {
   ALL_VNODES,
   betweenChildren,
   COMPONENTS_AND_ELEMENTS,
+  countChildren,
   eachChild,
   everyChild,
   extractSingleChild,

packages/vue-vnode-utils/src/iterators.ts

@@ -429,3 +429,20 @@ export const extractSingleChild = (children: VNodeArrayChildren): VNode | undefi
 
   return node
 }
+
+export const countChildren = (
+  children: VNodeArrayChildren,
+  options: IterationOptions = ALL_VNODES
+) => {
+  if (__DEV__) {
+    checkArguments('count', [children, options], ['array', 'object'])
+  }
+
+  let count = 0
+
+  someChildInternal(children, () => {
+    ++count
+  }, options)
+
+  return count
+}