關閉在JavaScript中

Question

我試圖重現這裏的IIEF的例子循環：

Understand JavaScript Closures With Ease

編輯

這下3.閉包走了歪

這是我的代碼：

var myArray = ["a", "b", "c"]; 

function doSomething(someArray) { 
    var counter = 10; 
    for (var i = 0; i < someArray.length; i++) { 
    someArray[i] = function(inner_i) { 
     return function() { 
     return counter += inner_i; 
     }(); 
    }(i); 
    } 
    return someArray; 
} 

var newArray = doSomething(myArray); 
console.log(newArray[0]); 
console.log(newArray[1]); 
console.log(newArray[2]); 

輸出是

10 
11 
13 

，而不是

10 
11 
12 

我在做什麼不同？

Answer 1

結果沒有錯，因爲您在每次迭代中更新counter的值。相反，只需返回counter和i的總和即可。

var myArray = ["a", "b", "c"]; 
 

 
function doSomething(someArray) { 
 
    var counter = 10; 
 
    for (var i = 0; i < someArray.length; i++) { 
 

 
    someArray[i] = function(inner_i) { 
 
     return function() { 
 
     return counter + inner_i; 
 
     }(); 
 
    }(i); 
 
    } 
 

 
    return someArray; 
 
} 
 

 
var newArray = doSomething(myArray); 
 
console.log(newArray[0]); 
 
console.log(newArray[1]); 
 
console.log(newArray[2]);