app.js

//Bubble Sorting.  Ascending order

let unsorted = [4, 6, 3, 1, 9];
console.log(unsorted);

// Sorting numbers.
let sorted = [4, 6, 3, 1, 9];
for (let i = 0; i < 4; i++) {         // 4 times chalei ga (0,1,2,3)
//for (let j = 0; j <= 3 ; j++) {  // aiei bhi likh saktei hai condition mai  -i koo remove kar kai bhi. Not Good Practice. 
  for (let j = 0; j <= 3 - i; j++) {  // 4 times chalei ga condition mai equal ka sign hai.
    if (sorted[j] > sorted[j + 1]) {  // sorted[0] > sorted[1] = 4 > 6
       // Swap                        // sorted[1] > sorted[2] = 6 > 3 condition true
      let k = sorted[j];          // k = 6 ;
       sorted[j] = sorted[j + 1];  // 6 = 3 ;
      sorted[j + 1] = k;          // 3 = 6 ;
    }
  }
}
console.log(sorted);   // Output = [1, 3, 4, 6, 9]