Longest Digits Prefix

Given a string, output its longest which contains only digits.

Example

For inputString = "123aa1", the output should be

longest_digits_prefix(inputString) = "123"

Solution

PYTHON

def longest_digits_prefix(input_string):
    prefix = ''
    for s in input_string:
        if s.isdigit():
            prefix += s
        else:
            break
    return prefix


print(longest_digits_prefix('123aa1'))

JAVASCRIPT

function longestDigitsPrefix(inputString) {
  let result = '';
  for (let i = 0; i < inputString.length; i++) {
    if (isNaN(parseInt(inputString[i]))) {
      break;
    }
    result += inputString[i];
  }
  return result;
}

console.log(longestDigitsPrefix('123aa1'));