Change to pass undefined, not null

Author: wooorm

index.test-d.ts

@@ -46,15 +46,15 @@ visit(sampleTree)
 // ## No test
 visit(sampleTree, function (node, index, parent) {
   expectType<Nodes>(node)
-  expectType<number | null>(index)
-  expectType<Parents | null>(parent)
+  expectType<number | undefined>(index)
+  expectType<Parents | undefined>(parent)
 })
 
 visit(implicitTree, function (node, index, parent) {
   // Objects are too loose.
   expectAssignable<Node>(node)
   expectNotType<Node>(node)
-  expectType<number | null>(index)
+  expectType<number | undefined>(index)
   expectType<never>(parent)
 })
 
@@ -63,8 +63,10 @@ visit(implicitTree, function (node, index, parent) {
 // Knows it’s a heading and its parents.
 visit(sampleTree, 'heading', function (node, index, parent) {
   expectType<Heading>(node)
-  expectType<number | null>(index)
-  expectType<Blockquote | FootnoteDefinition | ListItem | Root | null>(parent)
+  expectType<number | undefined>(index)
+  expectType<
+    Blockquote | FootnoteDefinition | ListItem | Root | undefined
+  >(parent)
 })
 
 // Not in tree.
@@ -83,8 +85,8 @@ visit(implicitTree, 'heading', function (node, index, parent) {
 
 visit(sampleTree, 'tableCell', function (node, index, parent) {
   expectType<TableCell>(node)
-  expectType<number | null>(index)
-  expectType<Root | TableRow | null>(parent)
+  expectType<number | undefined>(index)
+  expectType<Root | TableRow | undefined>(parent)
 })
 
 // ## Props test
@@ -203,7 +205,7 @@ visit(sampleTree, 'tableCell', function (node) {
       | LinkReference
       | Strong
       | TableCell
-      | null
+      | undefined
     >(parent)
   })
 })

lib/index.js

@@ -43,9 +43,9 @@
  *   traversed.
  * @param {Visited} node
  *   Found node.
- * @param {Visited extends UnistNode ? number | null : never} index
+ * @param {Visited extends UnistNode ? number | undefined : never} index
  *   Index of `node` in `parent`.
- * @param {Ancestor extends UnistNode ? Ancestor | null : never} parent
+ * @param {Ancestor extends UnistNode ? Ancestor | undefined : never} parent
  *   Parent of `node`.
  * @returns {VisitorResult}
  *   What to do next.
@@ -187,7 +187,7 @@ export function visit(tree, testOrVisitor, visitorOrReverse, maybeReverse) {
    */
   function overload(node, parents) {
     const parent = parents[parents.length - 1]
-    const index = parent ? parent.children.indexOf(node) : null
+    const index = parent ? parent.children.indexOf(node) : undefined
     return visitor(node, index, parent)
   }
 }

readme.md

@@ -162,9 +162,9 @@ traversed.
 
 *   `node` ([`Node`][node])
     — found node
-*   `index` (`number` or `null`)
+*   `index` (`number` or `undefined`)
     — index of `node` in `parent`
-*   `parent` ([`Node`][node] or `null`)
+*   `parent` ([`Node`][node] or `undefined`)
     — parent of `node`
 
 ###### Returns

test.js

@@ -145,6 +145,7 @@ test('visit', async function (t) {
 
       assert.equal(n, 3, 'should visit all passing nodes')
 
+      // To do: when `unist-util-is` updates, we can drop `null`.
       /**
        * @param {Node} _
        * @param {number | null | undefined} index