Merge pull request jsmapr1#4 from jmarking/master

jsmapr1 · web-flow · commit a7ced4922664 · 2019-04-11T08:48:04.000-05:00
Fix erroneous behavior if removable does not exist in the items array.
diff --git a/arrays/spread/slice.js b/arrays/spread/slice.js
@@ -2,8 +2,11 @@
 
 //  # START:removeItemSlice
 function removeItem(items, removable) {
-  const index = items.indexOf(removable);
-  return items.slice(0, index).concat(items.slice(index + 1));
+  if (items.includes(removable)) {
+    const index = items.indexOf(removable);
+    return items.slice(0, index).concat(items.slice(index + 1));
+  }
+  return items;
 }
 //  # END:removeItemSlice
 
diff --git a/arrays/spread/splice.js b/arrays/spread/splice.js
@@ -1,8 +1,10 @@
 /* eslint-disable no-unused-vars */
 //  # START:removeItemSplice
 function removeItem(items, removable) {
-  const index = items.indexOf(removable);
-  items.splice(index, 1);
+  if (items.includes(removable)) {
+    const index = items.indexOf(removable);
+    items.splice(index, 1);
+  }
   return items;
 }
 //  # END:removeItemSplice
diff --git a/arrays/spread/spread.js b/arrays/spread/spread.js
@@ -2,8 +2,11 @@
 
 //  # START:removeItemSpread
 function removeItem(items, removable) {
-  const index = items.indexOf(removable);
-  return [...items.slice(0, index), ...items.slice(index + 1)];
+  if (items.includes(removable)) {
+    const index = items.indexOf(removable);
+    return [...items.slice(0, index), ...items.slice(index + 1)];
+  }
+  return items;
 }
 //  # END:removeItemSpread
 
diff --git a/arrays/spread/spread.spec.js b/arrays/spread/spread.spec.js
@@ -53,4 +53,28 @@ describe('spread operator', () => {
     expect(formatBook(...values)).toEqual('Reasons and Persons by Derek Parfit $19.99');
     expect(formatBook(...Object.values(book))).toEqual('Reasons and Persons by Derek Parfit $19.99');
   });
+
+  it('should not modify with a loop', () => {
+    const before = ['apple', 'banana', 'orange'];
+    const after = ['apple', 'banana', 'orange'];
+    expect(removeItemProblem(before, 'peach')).toEqual(after);
+  });
+
+  it('should not modify with a slice', () => {
+    const before = ['apple', 'banana', 'orange'];
+    const after = ['apple', 'banana', 'orange'];
+    expect(removeItemSlice(before, 'peach')).toEqual(after);
+  });
+
+  it('should not modify with a splice', () => {
+    const before = ['apple', 'banana', 'orange'];
+    const after = ['apple', 'banana', 'orange'];
+    expect(removeItemSplice(before, 'peach')).toEqual(after);
+  });
+
+  it('should not modify with a spread', () => {
+    const before = ['apple', 'banana', 'orange'];
+    const after = ['apple', 'banana', 'orange'];
+    expect(removeItem(before, 'peach')).toEqual(after);
+  });
 });
