타입스크립트 filter, map, reduce (함수형프로그래밍)
type FooD = { name:string, price:number, quantity:number, selected:boolean};const foods:FooD[] = [ { name:"피카츄돈가츠", price:10000, quantity:1, selected:true }, { name:"아싸츄", price:4000, quantity:2, selected:true }]const sum = (foods:FooD[]) => foods.filter(fod=>fod.selected).map(fod=>fod.quantity).reduce((a,b) => a+b,0..