feat: Add Question 479 - Purpose of the .at() method

README.md

@@ -506,7 +506,11 @@
 | 475 | [What are shadowing and illegal shadowing?](#what-are-shadowing-and-illegal-shadowing) |
 | 476 | [Why is it important to remove event listeners after use?](#why-is-it-important-to-remove-event-listeners-after-use) |
 | 477 | [What is structuredClone and how is it used for deep copying objects?](#what-is-structuredclone-and-how-is-it-used-for-deep-copying-objects) |
+
+| 477 | [What is the difference btw == & === in java script?](#what-is-structuredclone-operators) |
+
 | 478 | [What is the difference between const and Object.freeze](#what-is-the-difference-between-const-and-objectfreeze) |
+
 <!-- TOC_END -->
 
 <!-- QUESTIONS_START -->
@@ -9553,36 +9557,36 @@ Common use cases and benefits:
 
    **[⬆ Back to Top](#table-of-contents)**
 
-478. ### What is the difference between const and Object.freeze
-
-     The main difference is that `const` applies to **variables** (bindings), while `Object.freeze()` applies to **values** (objects).
+479. ### What is the purpose of the at() method
 
-     1. **`const`**: Prevents the reassignment of a variable identifier. It ensures that the variable name always points to the same memory reference. However, if the variable holds an object or array, the *contents* of that object can still be modified.
-     2. **`Object.freeze()`**: Prevents the modification of an object's properties. It makes the object immutable (you cannot add, remove, or change properties), but it does not affect the variable assignment itself (unless the variable is also declared with `const`).
+The `at()` method takes an integer value and returns the item at that index, allowing for positive and negative integers.
+Negative integers count back from the last item.
 
-     **Example:**
+Prior to this method, accessing the last element of an array required using array[array.length - 1].
+The at() method makes this much cleaner and supports both **Arrays** and **Strings**.
 
-     ```javascript
-       // Case 1: Using const (Reassignment prevented, Mutation allowed)
-       const person = { name: "John" };
-       person.name = "Doe"; // ✅ Allowed: The object is mutable
-       console.log(person.name); // "Doe"
+**Key Features:**
+1. *Positive Index:* Works the same as square bracket notation [].
+2. *Negative Index:* Counts from the end of the array (e.g., -1 is the last element).
 
-       // person = { name: "Jane" }; // ❌ Error: Assignment to constant variable
+**Example:**
 
-       // Case 2: Using Object.freeze (Reassignment allowed, Mutation prevented)
-       let profile = { name: "John" };
-       Object.freeze(profile);
+```javascript
+const colors = ["Red", "Green", "Blue"];
 
-       profile.name = "Doe"; // ❌ Ignored (or throws TypeError in strict mode)
-       console.log(profile.name); // "John"
+// Old way to get the last element
+console.log(colors[colors.length - 1]); // "Blue"
 
-       profile = { name: "Jane" }; // ✅ Allowed: 'profile' is declared with 'let'
-       console.log(profile.name); // "Jane"
-       
+// Using at()
+console.log(colors.at(-1)); // "Blue"
+console.log(colors.at(-2)); // "Green"
 
-      **[⬆ Back to Top](#table-of-contents)**
+// It also works on Strings
+const sentence = "Hello";
+console.log(sentence.at(-1)); // "o"
 
+// Comparing with bracket notation for negative index
+console.log(colors[-1]); // undefined (Bracket notation looks for property "-1")
 
 <!-- QUESTIONS_END -->
 ### Coding Exercise