const product = [
  {id:1,product:'book',price:'100',stock:2},
  {id:2,product:'shoes',price:'40',stock:0},
  {id:3,product:'laptop',price:'30',stock:1},
  {id:4,product:'tablet',price:'20',stock:4},
  {id:5,product:'smartphone',price:'50',stock:2}
]


//sum of stok
const Total = (products) => {
   return product.reduce((prevVal, elem) => prevVal + elem.stock, 0);

}


const checkStock = (products,available='true') => {
    return  product.filter((data)=>{
       return data.stock !=0
    })
}

console.log(Total(product))
console.log(checkStock(product))