### Example 1: Manipulate function argument until some condition is true

The following is a solution to this kata which describes the challenge as:

So, your task is to sum up all the digits in string, possibly multiple times, till you get a one digit result. You should then return it as a string. The input will be always valid.

``````const str = '1234'
digitSum(str) // returns 1

/* 1 + 2 + 3 + 4 = 10 <= this result doesn't have one digit => 1 + 0 = 1 */``````
``````function digitSum(numStr) {
// Get digits sum (e.g., 10)
const digitsSum = numStr.split('').reduce((sum, num) => sum + Number(num), 0).toString()

// If sum.length === 1, return sum
if (digitsSum.length === 1)  {
return digitsSum
}

// Else, call function again
return digitSum(digitsSum)
}``````

### Example 2

Solution to kata. Need to elaborate on how this works.

``````function getElement(array, indices) {
if (indices.length === 1) {
return array[indices]
}

return getElement(array[indices], indices. Slice(1))
}``````