Find longest common string prefix

longestPrefix.js

// Find the longest common prefix
const longestPrefix = (arr) => {
  // Handle a couple of invalid inputs
  if (!arr || !Array.isArray(arr) || arr.length === 0) {
    return '';
  // Bypass the loop if there's only one element in the array
  } else if (arr.length === 1) {
    return arr[0];
  }
  
  let prefix = '';
  const firstWord = arr[0];
  // We only need to loop through the first word
  for (let i = 0; i < firstWord.length; i++) {
    // Every word has to have the same character at the same location for the loop to continue
    if (arr.every(x => x[i] === firstWord[i])) {
      // If they match, append the character to the prefix
      prefix += firstWord[i];
    } else {
      // If they don't match, boot us out of the loop.
      break;
    }
  }
  
  return prefix;
};

console.log(longestPrefix(["cranberry","crawfish","crap"]))
console.log(longestPrefix(["parrot", "poodle", "fish"]))