An example of moving an item from one Array to another Array

moveItemDebug.js

let dinnerFood = ['salad', 'soup', 'casserole'];
let breakfastFood = ['omelet', 'pancakes', 'fruit'];

console.log(`From array:  ${breakfastFood}`);
console.log(`To array:  ${dinnerFood}`);

function moveItem(itemToMove , fromArray, toArray) {

  function extractItem() {
    // we know the item is in the starting array
    function isItem(currentItem) {
      // if the two items are the same
      // then return the item to the caller
      return itemToMove === currentItem;
    }

    let theItem = fromArray.find(isItem);

    // ['salad', 'soup', 'casserole']
    // ['salad', 'casserole']
    // let start = dinnerFood.slice(0, 1) => ['salad']
    // let end   = dinnerFood.slice(2) => ['casserole']
    let index = fromArray.indexOf(itemToMove);
    let start = fromArray.slice(0, index);
    let end = fromArray.slice(index + 1);
    console.log(start, end);

    let result = start.concat(end);
    console.log(result);
    fromArray = result;
    return theItem;
  }

  if (fromArray.includes(itemToMove) && !toArray.includes(itemToMove)) {
    console.log("FIRST RUNNING")
    let theItem = extractItem(fromArray);
    toArray.push(theItem);
    return true
  } else if (fromArray.includes(itemToMove)) {
    console.log("SECOND RUNNING");
    extractItem(fromArray);
  }
  
  return false;
}

moveItem("pancakes", breakfastFood, dinnerFood);
moveItem("pancakes", breakfastFood, dinnerFood);

console.log(`From array:  ${breakfastFood}`);
console.log(`To array:  ${dinnerFood}`);

moveItemFromArray.js

let dinnerFood = ['salad', 'soup', 'casserole'];
let breakfastFood = ['omelet', 'pancakes', 'fruit'];

console.log(`From array:  ${breakfastFood}`);
console.log(`To array:  ${dinnerFood}`);

function moveItem(itemToMove , fromArray, toArray) {
  if (fromArray.includes(itemToMove) && !toArray.includes(itemToMove)) {
    // we know the item is in the starting array
    function isItem(currentItem) {
      // if the two items are the same
      // then return the item to the caller
      return itemToMove === currentItem;
    }

    let theItem = fromArray.find(isItem);

    // ['salad', 'soup', 'casserole']
    // ['salad', 'casserole']
    // let start = dinnerFood.slice(0, 1) => ['salad']
    // let end   = dinnerFood.slice(2) => ['casserole']
    let index = fromArray.indexOf(itemToMove);
    let start = fromArray.slice(0, index);
    let end   = fromArray.slice(index + 1);

    fromArray = start.concat(end);
    toArray.push(theItem);
    return true
  }
  
  return false;
}

moveItem('pancakes', breakfastFood, dinnerFood);

console.log(`From array:  ${breakfastFood}`);
console.log(`To array:  ${dinnerFood}`);

moveItemWithoutDuplicates.js

let dinnerFood = ['salad', 'soup', 'casserole'];
let breakfastFood = ['omelet', 'pancakes', 'fruit'];

console.log(`From array:  ${breakfastFood}`);
console.log(`To array:  ${dinnerFood}`);

function moveItem(itemToMove , fromArray, toArray) {

  function extractItem() {
    // we know the item is in the starting array
    function isItem(currentItem) {
      // if the two items are the same
      // then return the item to the caller
      return itemToMove === currentItem;
    }

    let theItem = fromArray.find(isItem);

    // ['salad', 'soup', 'casserole']
    // ['salad', 'casserole']
    // let start = dinnerFood.slice(0, 1) => ['salad']
    // let end   = dinnerFood.slice(2) => ['casserole']
    let index = fromArray.indexOf(itemToMove);
    let start = fromArray.slice(0, index);
    let end = fromArray.slice(index + 1);

    fromArray = start.concat(end);
    return theItem;
  }

  if (fromArray.includes(itemToMove) && !toArray.includes(itemToMove)) {
    let theItem = extractItem();
    toArray.push(theItem);
    return true
  } else if (fromArray.includes(itemToMove)) {
    extractItem();
  }
  
  return false;
}

moveItem("pancakes", breakfastFood, dinnerFood);
moveItem("pancakes", breakfastFood, dinnerFood);

console.log(`From array:  ${breakfastFood}`);
console.log(`To array:  ${dinnerFood}`);