bigOn.js

// return true if an item exists in list
// and false if it doesn't
var fruits = ["Banana", "Orange", "Apple", "Mango"];
var numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14];

function checkItemInList(item, list) {
    return list.includes(item);
}

console.log('Is Mango in Fruit List:', checkItemInList('Mango', fruits));      // true
console.log('Is Avocado in Fruit List:', checkItemInList('Avocado', fruits));  // false

console.log('Is 14 in numbers list:', checkItemInList(14, numbers));           // true
console.log('Is 15 in numbers list:', checkItemInList(15, numbers));           // false

// **********************************************************************************
// - In the case the run time of checkItemInList is O(n)
// - n being the number of item in the array list
// - Big O Notaion favor the worse case scenaior: the item we are looking for 
// - is the last item in the list array
// **********************************************************************************