find, filter

//[19]: 조건에 맞는 첫번째 요소 찾기 --> fid() --> 명세서 --> 콜백함수 사용
const testAr19  = [10, 20, 30, 40, 50, 60, 70, 80, 90, 100];
console.log(testAr19);

//find() 메서드는 조건에 만족하는 첫 번째 요소의 값을 반환 --> 결과가 없다면 undefined 반환
const found = testAr19.find(function(element) {

//할 일 처리 ---> return
return element >= 71;
});

console.log(found); // 80 --> 주의해서 결과값 확인해야 함


const found2 = testAr19.find(function(element) {

//할 일 처리 ---> return
return element >= 101;
});

console.log(found2); // undefined --> 주의해서 결과값 확인해야 함

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//find() vs filter() 비교(차이점)
//find() 메서드  --> 찾는 즉시 첫 번째 요소의 값을 반환. 더 이상 순회하지 않음(X)
//filter() 메서드 --> 계속 순회함 --> 조건에 맞는 값을 다 찾아 줌

const testAr20  = [10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 50];
let arData_loop_count = 0;

//반복횟수
const rst1 = testAr20.filter(ele => {

//할 일 처리 --> return
arData_loop_count++;
return ele == 50;
});

console.log("해당 메서드의 반복 횟수는 = " + arData_loop_count); // 11
console.log(rst1);  // [50, 50]
console.log(typeof rst1); //object

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//[20]: 객체를 담고 있는 배열에서 특정 객체 찾기 --> find()

const cars = [
{name: 'Tesla', price: 50000},
{name: 'Benz', price: 80000},
{name: 'BMW', price: 70000},
{name: 'Audi', price: 60000}
];

console.log('-----------------------------------------------------find() - 콜백함수 외부에');

//콜백함수 외부에
function searchValue1(car) {
return car.name === 'Tesla';
}

//호출
console.log(cars.find(searchValue1)); // {"name": "Tesla","price": 50000}
console.log(cars.filter(searchValue1)); // {"name": "Tesla","price": 50000}


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const cars = [
{name: 'Tesla', price: 50000},
{name: 'Benz', price: 80000},
{name: 'BMW', price: 70000},
{name: 'Audi', price: 60000}
];

console.log('-----------------------------------------------------find() - 콜백함수 내부에');

//콜백함수 내부에
let searchValue2 = cars.find(function(ele){

//할 일 처리 --> return
return ele.name === 'Audi';
});

//호출
console.log(searchValue2); // {"name": "Audi","price": 60000}

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console.log('-----------------------------------------------------find() - 화살표 함수');

const cars = [
{name: 'Tesla', price: 50000},
{name: 'Benz', price: 80000},
{name: 'BMW', price: 70000},
{name: 'Audi', price: 60000}
];

//화살표 함수(=>)
let searchValue3 = cars.find(ele=>ele.name === 'Benz');
console.log(searchValue3); // {"name": "Benz","price": 80000}