Using var to intentionally leak a variable

Is the following pattern ok in javascript, or is this frowned upon? And if the latter, what would be a better approach?

function arithmetic_sum(n) {
    for (var [i, sum] = [0, 0]; i <= n; sum += i++);
    return sum;
}

console.log(arithmetic_sum(10));
// 55

>Solution :

This is valid JavaScript.

Some people may like that, but it’s a bit outdated and mixing old and new styles (var, but in combination with destructuring).

Also having code inside the interation clause of the for loop can be confusing.

I would prefer this instead:

function arithmetic_sum(n) {
    let sum = 0;
    for (let i = 0; i <= n; i++) {
      sum += i;
    }
    return sum;
}

console.log(arithmetic_sum(10));
// 55