未捕獲TypeError：無法設置未定義的屬性'0'

Question

我想插入一個值到數組中，但是當我嘗試插入值時，它給了我Connot set屬性'0'的未定義。但顯然我已經定義了陣列。

錯誤行：

this.enemyMinions[i] = new EnemyCombatMinion(new Minion(enemyMinionInfo[0], 0, enemyMinionInfo[1], enemyMinionInfo[2], enemyMinionInfo[3], 0, 0, 0, 0, 0, 0)); 

這是整個代碼：

function Combat() { 
    this.enemyMinions = []; 
    this.playerMinions = []; 
    this.currentEnemyMinion = null; 
    this.currentPlayerMinion = null; 
} 

Combat.prototype.initialize = function() { 
    var o = 0; 
    for(var i = 0; i < partySlots.length; i++) { 
    if(partySlots[i]) { 
     this.playerMinions[o] = PlayerCombatMinion(partySlots[i]); 
     o++; 
    } 
    } 
    this.currentPlayerMinion = this.playerMinions[0]; 

    $.ajax({ 
     url: "./api/generateEnemyCombatMinions.php", 
     cache: false 
    }) 
    .done(function(html) {   
     var response = html.split(":::"); 
     for(var i = 0; i < response.length; i++) { 
     var enemyMinionInfo = response[i].split("::"); 
     this.enemyMinions[i] = new EnemyCombatMinion(new Minion(enemyMinionInfo[0], 0, enemyMinionInfo[1], enemyMinionInfo[2], enemyMinionInfo[3], 0, 0, 0, 0, 0, 0)); 
     } 
     alert(this.enemyMinions.length); 
    }); 

} 

正如你看到的，我宣佈this.enemyMinons在類的構造文字，並試圖定義初始化方法中的值。

Answer 1

done()回調不會使用您的Combat對象作爲this。保存一個指向initialize()函數中的對象的指針，以便稍後可以訪問該對象。

Combat.prototype.initialize = function() { 
    var o = 0; 
    for(var i = 0; i < partySlots.length; i++) { 
    if(partySlots[i]) { 
     this.playerMinions[o] = PlayerCombatMinion(partySlots[i]); 
     o++; 
    } 
    } 
    this.currentPlayerMinion = this.playerMinions[0]; 

    // this is new 
    var that= this; 

    $.ajax({ 
     url: "./api/generateEnemyCombatMinions.php", 
     cache: false 
    }) 
    .done(function(html) {   
     var response = html.split(":::"); 
     for(var i = 0; i < response.length; i++) { 
     var enemyMinionInfo = response[i].split("::"); 
     // use "that" here instead of "this" 
     that.enemyMinions[i] = new EnemyCombatMinion(new Minion(enemyMinionInfo[0], 0, enemyMinionInfo[1], enemyMinionInfo[2], enemyMinionInfo[3], 0, 0, 0, 0, 0, 0)); 
     } 
     alert(that.enemyMinions.length); 
    }); 

}