first-unique-character.js

function firstUniqueCharacter(text) {
  // split string into single characters
  let characters = String(text).split("")

  if (characters.length < 1) return 'Please input a non-empty string'

  // iterate through array, comparing each character to the rest

  // if found no match for a certain character after comparing to all other characters, return character at the end of first such iteration

  // for chatacters being compared
  for (let i = 0; i < characters.length; i++) {
    // for characters being compared with
    for (let j = 0; j < characters.length; j++) {
      // if not comparing to self
      if (!(i === j)) {
        // AND if similar, jump to next character to compare with the rest - as it's a repeat
        if (characters[i] === characters[j]) break
      }

      // if has come to the last character (also means we haven't found a match above)
      // return this character
      if (j === (characters.length - 1)) {
        return characters[i]
      }
    }
  }
}

console.log(firstUniqueCharacter('what is life'))