7kyuConsectiveItems.js

//You are given a list of unique integers arr, and two integers a and b. Your task is to find out whether or not a and b appear consecutively in arr, and return a boolean value (True if a and b are consecutive, False otherwise). It is guaranteed that a and b are both present in arr.

function consecutive(arr, a, b) {
    for (let i = 0; i < arr.length - 1; i++) {
      if ((arr[i] === a && arr[i + 1] === b) || (arr[i] === b && arr[i + 1] === a)) {
        return true;
      }
    } 
    return false;
}

//or

function consecutive(arr, a, b) {
  return Math.abs(arr.indexOf(a) - arr.indexOf(b)) == 1;
}

//or

const consecutive = (arr, a, b) => Math.abs(arr.indexOf(a) - arr.index(b)) == 1;