[SOLVED] Separating odd numbers in a string with '-'

Separating odd numbers in a string with '-'

I am attempting to take a string of numbers and iterate through that number. When there are two odd numbers adjacent to one another, I want to separate them with '-'.

For example, 999463 would become 9-9-9463.

const str = "999463"

const numberWithDash = []

for (let i = 0; i < str.length; i++) {
  if (str[i] % 2 !== 0 && str[i + 1] % 2 !== 0) {
    numberWithDash.push(str[i] + '-')
  } else {
    numberWithDash.push(str[i])
  }
};

console.log(numberWithDash.join(''))

This returns "9-9-9463-". Why is this adding an additional dash on the end of my code? I think this is because the final number in the string is odd, thereby it is being passed through the if statement, instead of the else stament.

If I amend 'i < str.length -1' then I just cut off the last number entirely, so that isn't right either. I think I need to make my if statement stricter by adding another condition to check if str[i] is a number, but not sure where to start.

Solution

You can just check whether you are at the end of the string. That makes sense anyway since you don't want to test the next character in that case (there is none):

if (str[i] % 2 !== 0 && i < str.length - 1 && str[i + 1] % 2 !== 0 ) {

I'd probably turn some things around to make it slightly easier to read: We always need to append the current digit. We sometimes want to append a dash.

for (let i = 0; i < str.length; i++) {
  numberWithDash.push(str[i])

  if (str[i] % 2 !== 0 && str[i + 1] % 2 !== 0 && i < str.length - 1) {
    numberWithDash.push('-')
  }
}