Copy characters Ⅱ

Given a value, return the value with its elements count increased by its own index number.

Sample Code:

function oneOne(str) {
// Enter your logic here...
}

Examples:

Input: 123
Output: '122333'
Explanation: Each element has been resurrected for i (index number) amount of times.

Input: 'Help'
Output: 'Heelllpppp'
Explanation: Each element has been resurrected for i (index number) amount of times.