fixed implementation and write test to prove its fixed

Author: fayaz551

Sprint-2/interpret/invert.js

@@ -6,7 +6,7 @@
 
 // E.g. invert({x : 10, y : 20}), target output: {"10": "x", "20": "y"}
 
-function invert(obj) {
+/* function invert(obj) {
   const invertedObj = {};
 
   for (const [key, value] of Object.entries(obj)) {
@@ -15,15 +15,42 @@ function invert(obj) {
 
   return invertedObj;
 }
+  */
 
 // a) What is the current return value when invert is called with { a : 1 }
+// the current return value is { key: 1 }
 
 // b) What is the current return value when invert is called with { a: 1, b: 2 }
+// the current return value is { key: 1, key: 2 }
 
 // c) What is the target return value when invert is called with {a : 1, b: 2}
+// the target return value is { "1": "a", "2": "b" }
 
 // c) What does Object.entries return? Why is it needed in this program?
+/* Object.entries returns an array of a given object's own enumerable string-keyed property [key, value] pairs.
+In this program, it is needed to iterate over the key-value pairs of the input object so that we can swap them and create the inverted object.
+*/
 
 // d) Explain why the current return value is different from the target output
+/* The current return value is different from the target output because in the current implementation,
+ we are assigning the value to a property named "key" in the inverted object,
+  which means that every key-value pair in the input object will overwrite the same "key" property in the inverted object.
+  As a result, only the last key-value pair from the input object will be reflected in the inverted object, leading to incorrect output.
+  To achieve the target output, we need to use the value from the input object as the key in the inverted object and 
+  the key from the input object as the value in the inverted object.
+*/
 
 // e) Fix the implementation of invert (and write tests to prove it's fixed!)
+function invert(obj) {
+  const invertedObj = {};
+
+  for (const [key, value] of Object.entries(obj)) {
+    invertedObj[value] = key;
+  }
+
+  return invertedObj;
+}
+
+
+
+expect(invert({ a: 1, b: 2 })).toEqual({ '1': 'a', '2': 'b' });