如何寫入雙號的功能，並通過他們作爲一個對象

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); 

當我運行我的代碼，它打印的時候我要的是它打印{1「10」：2,2：4， 3：6,4：8,5：10}。爲什麼會發生？

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); 

你原來的循環基本上是這...

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);