[자바스크립트] reduce

const numbers = [1, 2, 3, 4, 5]; // reduce 통해서 전체 합 구하기, // const sum = numbers.reduce( // (accumulator, current, index, array) => accumulator + current, // 0 // ); // console.log(sum); // avg = 평균구하기 const avg = numbers.reduce((accumulator, current, index, array) => { if (index === array.length - 1) { return (accumulator + current) / array.length; } return accumulator + current; }, 0); console.log(avg); ------------------------------------------------------------ const alphabets = ["a", "a", "a", "b", "c", "d"]; const counts = alphabets.reduce((acc, current) => { if (acc[current]) { acc[current] += 1; } else { acc[current] = 1; } return acc; }, {}); console.log(counts);