chore: import upstream snapshot with attribution

curriculum/challenges/english/blocks/basic-javascript/cf1111c1c11feddfaeb8bdef.md

@@ -0,0 +1,80 @@
+---
+id: cf1111c1c11feddfaeb8bdef
+title: Modify Array Data With Indexes
+challengeType: 1
+forumTopicId: 18241
+dashedName: modify-array-data-with-indexes
+---
+
+# --description--
+
+Unlike strings, the entries of arrays are <dfn>mutable</dfn> and can be changed freely, even if the array was declared with `const`.
+
+**Example**
+
+```js
+const ourArray = [50, 40, 30];
+ourArray[0] = 15;
+```
+
+`ourArray` now has the value `[15, 40, 30]`.
+
+**Note:** There shouldn't be any spaces between the array name and the square brackets, like `array [0]`. Although JavaScript is able to process this correctly, this may confuse other programmers reading your code.
+
+# --instructions--
+
+Modify the data stored at index `0` of `myArray` to a value of `45`.
+
+# --hints--
+
+`myArray` should now be `[45, 64, 99]`.
+
+```js
+assert(
+  (function () {
+    if (
+      typeof myArray != 'undefined' &&
+      myArray[0] == 45 &&
+      myArray[1] == 64 &&
+      myArray[2] == 99
+    ) {
+      return true;
+    } else {
+      return false;
+    }
+  })()
+);
+```
+
+You should be using correct index to modify the value in `myArray`.
+
+```js
+assert(
+  (function () {
+    if (__helpers.removeJSComments(code).match(/myArray\[0\]\s*=\s*/g)) {
+      return true;
+    } else {
+      return false;
+    }
+  })()
+);
+```
+
+# --seed--
+
+## --seed-contents--
+
+```js
+// Setup
+const myArray = [18, 64, 99];
+
+// Only change code below this line
+
+```
+
+# --solutions--
+
+```js
+const myArray = [18, 64, 99];
+myArray[0] = 45;
+```