An InventoryList to add, remove and get items in an inventory

inventoryList.js

function inventoryList(){
  return {
    items: [],
    add: function(item){
      if(this.items.includes(item)){
        return
      }
      this.items.push(item)
    },
    remove: function(item){
      if(this.items.includes(item)){
        let index = this.items.indexOf(item)
        if(index > -1){
          this.items.splice(index, 1)
        }
      }
    },
    getList: function(){
      return this.items
    },
  }
}

//have an inventory, a add function and a remove function, getList, return the items 
//in the inventory

const inventory = inventoryList();
// console.log(inventory.getList())
inventory.add('ketchup');
inventory.add('mayo')
inventory.add('mustard')

inventory.remove('mayo');
inventory.remove('tomato')

console.log(inventory.getList())

Resources.md

Here a couple of Resources that would help you understand the code.

1. Splice Array Method
2. This keyword
3. Array Methods