fix: variables.js file

Author: ExploitEngineer

part1 (Basics)/01_variables.js

@@ -1,101 +1,56 @@
-// using let (recommended for changeable values)
-let age = 20; // Declared and initialized with value 20
-age = 30;
+// variables.js
 
+// Using let (recommended for variables that can change)
+let age = 20;  // Declare and initialize variable
+age = 30;      // Update the value
 
-// using const (recommended for constant values)
-const pi = 3.14; // Declared and initialized. Value can't be changed.
 
-
-// using var (old way, Avoid using it), var also add itself to the window object
-var name = "John";
-
-
-
-// NOTE: Quizzez Time
-
-// INFO: First Quizz
-let a = 10;
-let b = 10;
-console.log(a == b); // true
-console.log(a === b); // true
-
-// INFO: Second Quizz
-let x = 3;
-console.log(x++); // 3
-console.log(++x); // 4
-
-
-// INFO: Idenfity the primitive data types
-let name = "Alice";
-let age1 = 30;
-let isHappy = true;
-let user = { name: "Bob" };
+// Using const (for constant values that should not change)
+const pi = 3.14;  // Declare and initialize constant
 
 
-// INFO: What will be the output
-console.log(typeof NaN); // number
-console.log(typeof null); // object
-
-
-// INFO: What will be the ouput of the following code
-let c = 10;
-let e = c++;
-let d = ++c;
-console.log(c, e, d); // 12, 10, 11
-
-
-// INFO: What will be the output of the following code ?
-console.log(typeof NaN); // number
-console.log(NaN === NaN); // false
-console.log(isNaN("Hello")); // true
-
-
-// INFO: What will be the printed to the console?
-let z = "10";
-let u = 5;
-console.log(x + y); // 105
-console.log(+x + y); // 15
-
+// Using var (old way, avoid if possible)
+// var declarations are function-scoped and can lead to unexpected behavior
+var name = "John";
 
-// INFO: What will be the output of the following code ?
-let person = { name: "Alice" };
-let anotherPerson = person;
-anotherPerson.name = "Bob";
-console.log(person.name); // "Bob"
 
+// Variable scope examples:
 
-// INFO: What is wrong with this code snippet?
-const score;
-score = 100;
-console.log(score); // Syntax Error
+// Block scope with let and const
+if (true) {
+  let blockScoped = "I exist only inside this block";
+  const constantScoped = "Also block-scoped";
+  console.log(blockScoped);    // Works here
+}
+// console.log(blockScoped);   // Error: blockScoped is not defined
 
 
-// INFO: What will be the result of this operation ?
-let num = 0.1 + 0.2;
-console.log(num === 0.3); // false
+// var is function scoped, not block scoped
+if (true) {
+  var functionScoped = "I exist inside the function or globally";
+}
+console.log(functionScoped);  // Works here (if not inside a function)
 
 
-// INFO: What will be the output of the following code ?
-let n = null;
-let i;
-console.log(typeof x); // object
-console.log(typeof y) // undefined
+// Variable naming rules:
+// - Can contain letters, digits, underscores, and dollar signs
+// - Cannot start with a digit
+// - Case sensitive (age and Age are different)
 
+// Example of valid variable names:
+let userName;
+let $amount;
+let _count;
 
-// INFO: What will be the output of the following code ?
-console.log([] + []); // ""
-console.log([] + {}); // [object object]
-console.log({} + []); // [object object]
+// Example of invalid variable name:
+// let 1stName;  // Syntax Error
 
 
-// INFO: What is the difference between these two?
-let main = 0;
-let actual = new Number(0);
-console.log(main == actual); // false
-console.log(main === actual); // true
+// Variables declared without let, const, or var become global (avoid this)
+function wrongExample() {
+  someVar = 10;  // Declares a global variable unintentionally
+}
+wrongExample();
+console.log(someVar);  // 10 (global scope)
 
 
-// INFO: What will be the output of this code ?
-console.log(0.1 + 0.2 === 0.3);
-console.log(0.1 + 0.2); // false, 0.30000000000000004