javascript - 数値を2倍にしてオブジェクトに渡す関数を作成する方法

Question

numbers = [1,2,3,4,5];

function doubling(number) {
    number *= 2;
    return number;
}

obj = {};
for (var i = 0; i < numbers.length; i++)
    doubled = doubling(numbers[i]);
    obj[numbers[i]] = doubled;
    console.log(obj);

コードを実行すると、{1:2, 2:4, 3:6, 4:8, 5:10} を出力したいときに「10」が出力されます。なぜこれが起こるのですか？

Answer 1

function doubling(number) {
    number *= 2;
    return number;
}

obj = {};

// your problem was here you were missing the curly braces
// so it was only executing the first line in the loop
for (var i = 0; i < numbers.length; i++) {
    doubled = doubling(numbers[i]);
    obj[numbers[i]] = doubled;
}
console.log(obj);

あなたの元のループは基本的にこれでした...

for (var i = 0; i < numbers.length; i++) {
    doubled = doubling(numbers[i]);
}
obj[numbers[i]] = doubled;  // numbers[i] is undefined so it 
                            // sets obj[undefined] = 10 
                            // (the value of double after the loop)
console.log(obj);