Change to return undefined

lib/index.js

@@ -17,24 +17,23 @@ import {convert} from 'unist-util-is'
  * @param {Parent} parent
  * @param {Node | number} index
  * @param {import('unist-util-is').PredicateTest<Kind>} test
- * @returns {Kind | null}
+ * @returns {Kind | undefined}
  *
  * @overload
  * @param {Parent} parent
  * @param {Node | number} index
  * @param {Test} [test]
- * @returns {Node | null}
+ * @returns {Node | undefined}
  *
  * @param {Parent} parent
  *   Parent node.
  * @param {Node | number} index
  *   Child of `parent`, or it’s index.
  * @param {Test} [test]
  *   `unist-util-is`-compatible test.
- * @returns {Node | null}
- *   Child of `parent` or `null`.
+ * @returns {Node | undefined}
+ *   Child of `parent` or `undefined`.
  */
-// To do: next major: return undefined.
 export function findBefore(parent, index, test) {
   const is = convert(test)
 
@@ -65,5 +64,5 @@ export function findBefore(parent, index, test) {
     }
   }
 
-  return null
+  return undefined
 }

readme.md

@@ -108,7 +108,7 @@ that passes `test`.
 
 ###### Returns
 
-Child of `parent` ([`Node`][node]) or `null`.
+Child of `parent` ([`Node`][node]) or `undefined`.
 
 ## Types
 

test.js

@@ -89,7 +89,7 @@ test('`findBefore`', async function (t) {
   await t.test(
     'should return the preceding node when without `test` (#3)',
     async function () {
-      assert.equal(findBefore(paragraph, 0), null)
+      assert.equal(findBefore(paragraph, 0), undefined)
     }
   )
 
@@ -117,21 +117,21 @@ test('`findBefore`', async function (t) {
   await t.test(
     'should return `node` when given a `node` and existing (#4)',
     async function () {
-      assert.equal(findBefore(paragraph, head, head), null)
+      assert.equal(findBefore(paragraph, head, head), undefined)
     }
   )
 
   await t.test(
     'should return `node` when given a `node` and existing (#5)',
     async function () {
-      assert.equal(findBefore(paragraph, 0, head), null)
+      assert.equal(findBefore(paragraph, 0, head), undefined)
     }
   )
 
   await t.test(
     'should return `node` when given a `node` and existing (#6)',
     async function () {
-      assert.equal(findBefore(paragraph, 1, next), null)
+      assert.equal(findBefore(paragraph, 1, next), undefined)
     }
   )
 
@@ -145,7 +145,7 @@ test('`findBefore`', async function (t) {
   await t.test(
     'should return a child when given a `type` and existing (#2)',
     async function () {
-      assert.equal(findBefore(paragraph, 3, 'strong'), null)
+      assert.equal(findBefore(paragraph, 3, 'strong'), undefined)
     }
   )
 
@@ -162,7 +162,10 @@ test('`findBefore`', async function (t) {
   await t.test(
     'should return a child when given a `type` and existing (#4)',
     async function () {
-      assert.equal(findBefore(paragraph, paragraph.children[3], 'strong'), null)
+      assert.equal(
+        findBefore(paragraph, paragraph.children[3], 'strong'),
+        undefined
+      )
     }
   )
 
@@ -176,7 +179,7 @@ test('`findBefore`', async function (t) {
   await t.test(
     'should return a child when given a `test` and existing (#2)',
     async function () {
-      assert.equal(findBefore(paragraph, 3, check), null)
+      assert.equal(findBefore(paragraph, 3, check), undefined)
     }
   )
 
@@ -193,7 +196,10 @@ test('`findBefore`', async function (t) {
   await t.test(
     'should return a child when given a `test` and existing (#4)',
     async function () {
-      assert.equal(findBefore(paragraph, paragraph.children[3], check), null)
+      assert.equal(
+        findBefore(paragraph, paragraph.children[3], check),
+        undefined
+      )
     }
   )
 })