Invert Excercise

Author: Della-Bella

Sprint-2/interpret/invert.js

@@ -6,24 +6,42 @@
 
 // E.g. invert({x : 10, y : 20}), target output: {"10": "x", "20": "y"}
 
-function invert(obj) {
-  const invertedObj = {};
+// function invert(obj) {
+//   const invertedObj = {};
 
-  for (const [key, value] of Object.entries(obj)) {
-    invertedObj.key = value;
-  }
+//   for (const [key, value] of Object.entries(obj)) {
+//     invertedObj.key = value;
+//   }
 
-  return invertedObj;
-}
+//   return invertedObj;
+// }
 
 // a) What is the current return value when invert is called with { a : 1 }
+// 1 
 
 // b) What is the current return value when invert is called with { a: 1, b: 2 }
+///2
 
 // c) What is the target return value when invert is called with {a : 1, b: 2}
+//"1": "a", "2": "b" 
 
 // c) What does Object.entries return? Why is it needed in this program?
+//Object.entries({ a: 1, b: 2 })  // Returns: [["a", 1], ["b", 2]]
+// It converts an object to an array of [key, value] pairs so you can loop through them.
 
 // d) Explain why the current return value is different from the target output
-
+// The bug is invertedObj.key = value — this literally creates a property named "key" 
+// instead of using the variable key. Also, it should swap: value becomes key, key becomes value.
 // 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; // Use [value] as key, key as value
+  }
+
+  return invertedObj;
+}
+
+module.exports = invert;

Sprint-2/interpret/invert.test.js

@@ -0,0 +1,17 @@
+const invert = require("./invert.js");
+
+test("inverts simple object", () => {
+  expect(invert({ a: 1 })).toEqual({ 1: "a" });
+});
+
+test("inverts multiple keys", () => {
+  expect(invert({ a: 1, b: 2 })).toEqual({ 1: "a", 2: "b" });
+});
+
+test("inverts x,y coordinates", () => {
+  expect(invert({ x: 10, y: 20 })).toEqual({ 10: "x", 20: "y" });
+});
+
+test("empty object returns empty", () => {
+  expect(invert({})).toEqual({});
+});