Fix issue with strings bookended with the same characters.

README.md

@@ -89,9 +89,9 @@ const result = striff(str1, str2);
 }
 ```
 
-### Strings w/ Duplicate Characters
+### Strings w/ Duplicate, Consecutive Characters
 
-Handling strings with duplicate, consecutive characters removed is a little weird. For strings whose characters were changed at the _end_, the indices will be grouped together at the end of the string.
+For strings whose characters were changed at the _end_, the indices will be grouped together at the end of the string.
 
 #### Input
 

package.json

@@ -2,7 +2,7 @@
   "name": "striff",
   "description": "Real simple string diffing.",
   "author": "Alex MacArthur (https://macarthur.me)",
-  "version": "1.0.3",
+  "version": "1.0.4",
   "main": "dist/index.umd.js",
   "module": "dist/index.es.js",
   "types": "dist/index.d.ts",

src/index.test.ts

@@ -169,3 +169,67 @@ describe("characters are changed and added", () => {
     ]);
   });
 });
+
+describe("multiple subsequent characters are in middle", () => {
+  it("simple example - added", () => {
+    const { added, removed } = striff("yxy", "yxxxy");
+
+    expect(added).toHaveLength(2);
+    expect(removed).toHaveLength(0);
+    expect(added).toEqual([
+      {
+        value: "x",
+        index: 2,
+      },
+      {
+        value: "x",
+        index: 3,
+      },
+    ]);
+  });
+
+  it("simple example - removed", () => {
+    const { added, removed } = striff("yxxxy", "yxy");
+
+    expect(removed).toHaveLength(2);
+    expect(added).toHaveLength(0);
+    expect(removed).toEqual([
+      {
+        value: "x",
+        index: 1,
+      },
+      {
+        value: "x",
+        index: 2,
+      },
+    ]);
+  });
+
+  it("line breaks are used", () => {
+      const str1 = `
+xxx
+22
+111
+`;
+      const str2 = `
+xxx
+2222
+111
+`;
+
+    const { added, removed } = striff(str1, str2);
+
+    expect(added).toHaveLength(2);
+    expect(removed).toHaveLength(0);
+    expect(added).toEqual([
+      {
+        value: "2",
+        index: 7,
+      },
+      {
+        value: "2",
+        index: 8,
+      }
+    ]);
+  });
+});

src/index.ts

@@ -33,13 +33,13 @@ let getDiff = (partsArr: Character[][], arr1: Character[], arr2: Character[]) =>
         let originalItem = arr1[partItem.index];
 
         // The first string character has already been matched
-        // with a second string character. Something's up.
-        // if (
-        //   originalItem.pointsTo &&
-        //   originalItem.pointsTo !== arr2[characterIndex].ref
-        // ) {
-        //   console.log('This one\'s already been matched to something, bud:', partItem.value);
-        // }
+        // with a second string character. Skip it!
+        if (
+          originalItem.pointsTo &&
+          originalItem.pointsTo !== arr2[characterIndex].ref
+        ) {
+          return;
+        }
 
         // Create a two-way binding between the characters:
         // Point the first string character to the second's ref.
@@ -51,7 +51,7 @@ let getDiff = (partsArr: Character[][], arr1: Character[], arr2: Character[]) =>
       // already matched the string and had their items set to the
       // `matched` store. We need to find those indicies and unset them.
       for (let i = result.index; i < result.index + pastMatchLength; i++) {
-        matched.delete(arr1[i].ref);
+        matched.delete(arr1[i]?.ref);
       }
 
       // Throw each of the matched characters into storage.
@@ -81,7 +81,6 @@ let getDiff = (partsArr: Character[][], arr1: Character[], arr2: Character[]) =>
 
 let striff = (str1: string, str2: string): DiffResult => {
   let strArr1 = toCharacters(str1);
-
   let strArr2 = toCharacters(str2).map((char, index) => {
     let str1Char = strArr1[index];