Account for duplicate values in an array

microsoft · Jan 24, 2025 · 4a4f5b0 · 4a4f5b0
1 parent aa60ff4
commit 4a4f5b0
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Showing 2 changed files with 20 additions and 14 deletions.
diff --git a/packages/web-components/fast-element/src/observation/arrays.spec.ts b/packages/web-components/fast-element/src/observation/arrays.spec.ts
@@ -140,10 +140,10 @@ describe("The ArrayObserver", () => {
         const array = [1, 2, 3, 4];
         array.reverse();
 
-        expect(array).members([4, 3, 2, 1]);
+        expect(array).ordered.members([4, 3, 2, 1]);
 
         Array.prototype.reverse.call(array);
-        expect(array).members([1, 2, 3, 4]);
+        expect(array).ordered.members([1, 2, 3, 4]);
 
         const observer = Observable.getNotifier<ArrayObserver>(array);
         let changeArgs: Sort[] | null = null;
@@ -155,7 +155,7 @@ describe("The ArrayObserver", () => {
         });
 
         array.reverse();
-        expect(array).members([4, 3, 2, 1]);
+        expect(array).ordered.members([4, 3, 2, 1]);
 
         await Updates.next();
 
@@ -170,7 +170,7 @@ describe("The ArrayObserver", () => {
         );
         changeArgs = null;
         array.reverse();
-        expect(array).members([1, 2, 3, 4]);
+        expect(array).ordered.members([1, 2, 3, 4]);
 
         await Updates.next();
 
@@ -227,15 +227,15 @@ describe("The ArrayObserver", () => {
 
     it("observes sorts", async () => {
         ArrayObserver.enable();
-        let array = [1, 3, 2, 4];
+        let array = [1, 3, 2, 4, 3];
 
         array.sort((a, b) => b - a);
-        expect(array).members([4, 3, 2, 1]);
+        expect(array).ordered.members([4, 3, 3, 2, 1]);
 
         Array.prototype.sort.call(array, (a, b) => a - b);
-        expect(array).members([1, 2, 3, 4]);
+        expect(array).ordered.members([1, 2, 3, 3, 4]);
 
-        array = [1, 3, 2, 4];
+        array = [1, 3, 2, 4, 3];
         const observer = Observable.getNotifier<ArrayObserver>(array);
         let changeArgs: Sort[] | null = null;
 
@@ -246,7 +246,7 @@ describe("The ArrayObserver", () => {
         });
 
         array.sort((a, b) => b - a);
-        expect(array).members([4, 3, 2, 1]);
+        expect(array).ordered.members([4, 3, 3, 2, 1]);
 
         await Updates.next();
 
@@ -255,6 +255,7 @@ describe("The ArrayObserver", () => {
             [
                 3,
                 1,
+                4,
                 2,
                 0
             ]

diff --git a/packages/web-components/fast-element/src/observation/arrays.ts b/packages/web-components/fast-element/src/observation/arrays.ts
@@ -700,18 +700,23 @@ let defaultMutationStrategy: SpliceStrategy = Object.freeze({
     ): any[] {
         const map = new Map();
 
-        for (let i = 0, ii = (array || []).length; i < ii; ++i) {
-            map.set(array[i], i);
+        for (let i = 0, ii = array.length; i < ii; ++i) {
+            const mapValue = map.get(array[i]) || [];
+
+            map.set(array[i], [...mapValue, i]);
         }
 
         const result = sort.apply(array, args);
 
         (array as any).sorted++;
 
         const sortedItems: number[] = [];
-        for (let i = 0, ii = (array || []).length; i < ii; ++i) {
-            const newIndex = map.get(array[i]);
-            sortedItems.push(newIndex);
+
+        for (let i = 0, ii = array.length; i < ii; ++i) {
+            const indexs = map.get(array[i]);
+            sortedItems.push(indexs[0]);
+
+            map.set(array[i], indexs.splice(1));
         }
 
         observer.addSort(new Sort(sortedItems));