I understand why CODE A returns a sequence of numbers (that's the loop process), but why is CODE B returning a summation?

```js
// CODE A:
let counter = '';
let i = 1;

do {
  counter = counter + i;
  i++;
} while (i < 15);
console.log(counter);
//1234567891011121314
```

```js
// CODE B:
let counter = 4;
let i = 1;

do {
  counter = counter + i;
  i++;
} while (i < 15);
console.log(counter);
//109
```