Fix bug when replacing and then not

Closes remarkjs/remark-github#40.

Author: wooorm

lib/index.js

@@ -137,6 +137,7 @@ export const findAndReplace =
         let start = 0
         // @ts-expect-error: TS is wrong, some of these children can be text.
         const index = parent.children.indexOf(node)
+        let change = false
         /** @type {Array<PhrasingContent>} */
         let nodes = []
         /** @type {number|undefined} */
@@ -160,9 +161,7 @@ export const findAndReplace =
             value = value.length > 0 ? {type: 'text', value} : undefined
           }
 
-          if (value === false) {
-            position = undefined
-          } else {
+          if (value !== false) {
             if (start !== position) {
               nodes.push({
                 type: 'text',
@@ -177,6 +176,7 @@ export const findAndReplace =
             }
 
             start = position + match[0].length
+            change = true
           }
 
           if (!find.global) {
@@ -186,14 +186,14 @@ export const findAndReplace =
           match = find.exec(node.value)
         }
 
-        if (position === undefined) {
-          nodes = [node]
-        } else {
+        if (change) {
           if (start < node.value.length) {
             nodes.push({type: 'text', value: node.value.slice(start)})
           }
 
           parent.children.splice(index, 1, ...nodes)
+        } else {
+          nodes = [node]
         }
 
         return index + nodes.length

test.js

@@ -236,6 +236,25 @@ test('findAndReplace', (t) => {
     'should not be order-sensitive with regexes'
   )
 
+  t.deepEqual(
+    findAndReplace(u('paragraph', [u('text', 'aaa bbb')]), [
+      [
+        /\b\w+\b/g,
+        function (/** @type {string} */ value) {
+          return value === 'aaa' ? u('strong', [u('text', value)]) : false
+        }
+      ]
+    ]),
+    {
+      type: 'paragraph',
+      children: [
+        {type: 'strong', children: [{type: 'text', value: 'aaa'}]},
+        {type: 'text', value: ' bbb'}
+      ]
+    },
+    'should support a match, and then a `false`'
+  )
+
   t.deepEqual(
     findAndReplace(create(), 'emphasis', () => false),
     u('paragraph', [