Javascript return undefined for an internal function Javascript return undefined for an internal function
I am doing an easy leetcode questions where we add one to a number whose digits are stored in an array. My logic works well but the returned value is undefined. Console gives the correct answer. Why? And how do I fix it? var plusOne = function(digits) { addNumber(digits.length - 1, 1, digits) function addNumber(index, value, digitsArr) { let sum = digitsArr[index] + value if(sum > 9) { let onesDigit = parseInt(sum.toString().charAt(1)) digitsArr[index] = onesDigit let twosDigit = parseInt(sum.toString().charAt(0)) addNumber(index-1, twosDigit, digitsArr) } else { digitsArr[index] = sum console.log(digitsArr) return digitsArr } } }; console.log(plusOne([1,2,9])) from Stackoverflow