如何在異步回調

Question

捕捉局部變量的值我有這個for循環：

for(var i = 0; i < characters.length; i++) 
{ 
    var character = characters[i]; 
    charService.get(character.name).then(function (characterData) 
    { 
     //I want character to be captured here, i.e. the character in the current loop 
     character.data = characterData; 
    }); 
} 

由於charService.get()是異步的，由執行回調的時候，character是數組（最後一個元素，因爲循環已經結束），因此以前的所有character都留在沒有數據的情況下。

如何保證回調裏面的character.data引用異步方法執行的循環的character？

Answer 1

使用Function.prototype.bind()嘗試.then()功能，設置爲character

for(var i = 0; i < characters.length; i++) 
{ 
    var character = characters[i]; 
    charService.get(character.name).then(function (characterData) 
    { 
     //I want character to be captured here, i.e. the character in the current loop 
     this.data = characterData; 
    }.bind(character)); 
} 

Answer 2

你可以把它包裝成函數

for(var i = 0; i < characters.length; i++) 
{ 
    (function(character){ 
    charService.get(character.name).then(function (characterData) 
    { 
     //I want character to be captured here, i.e. the character in the current loop 
     character.data = characterData; 
    }); 
    })(characters[i]); 
}