Change to return undefined, not null

Author: wooorm

lib/index.js

@@ -8,7 +8,7 @@
  *   Get a definition by identifier.
  * @param {string | null | undefined} [identifier]
  *   Identifier of definition (optional).
- * @returns {Definition | null}
+ * @returns {Definition | undefined}
  *   Definition corresponding to `identifier` or `null`.
  */
 
@@ -48,7 +48,7 @@ export function definitions(tree) {
   function definition(identifier) {
     const id = clean(identifier)
     // To do: next major: return `undefined` when not found.
-    return id && own.call(cache, id) ? cache[id] : null
+    return id && own.call(cache, id) ? cache[id] : undefined
   }
 }
 

readme.md

@@ -73,7 +73,7 @@ definition('example')
 // => {type: 'definition', 'title': 'Example', …}
 
 definition('foo')
-// => null
+// => undefined
 ```
 
 ## API
@@ -109,7 +109,7 @@ Get a definition by identifier (TypeScript type).
 ###### Returns
 
 Definition corresponding to `identifier` ([`Definition`][definition]) or
-`null`.
+`undefined`.
 
 ## Types
 

test.js

@@ -38,10 +38,10 @@ test('definitions', async function (t) {
     )
   })
 
-  await t.test('should return null when not found', async function () {
+  await t.test('should return `undefined` when not found', async function () {
     assert.equal(
       definitions(from('[example]: https://example.com "Example"'))('foo'),
-      null
+      undefined
     )
   })
 
@@ -75,7 +75,7 @@ test('definitions', async function (t) {
     async function () {
       assert.deepEqual(
         definitions(from('[__proto__]: https://proto.com "Proto"'))('toString'),
-        null
+        undefined
       )
     }
   )
@@ -98,7 +98,7 @@ test('definitions', async function (t) {
         definitions(
           from('[example]: https://one.com\n[example]: https://two.com')
         )(''),
-        null
+        undefined
       )
     }
   )