的javascript：通過局部變量的匿名函數

Question

問題：如何訪問shortcut或action或其他局部變量

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Java解決方案： 設置final改性劑，在匿名函數需要

目標源代碼變量：

//plugin.buttons is collection of button objects 
for (var i in plugin.buttons) { 
    var button = plugin.buttons[i]; 
    var icon = button.icon; 
    var text = button.text; 
    var shortcut = button.shortcut; 
    var action = button.action; //action is a function (or method) 

    if (shortcut != null && shortcut.length > 0) { 
     if ($.isFunction(action)) { 
      console.log(shortcut); //it's valid shortcut 
      //using jQuery hotkey plugin 
      $('div[contenteditable]').bind('keydown', shortcut, function() { 
       console.log(shortcut); //it's undefined 
       action.call(); //it's undefined also 
       return false; 
      }); 
     } 
    } 
} 

Answer 1

你可以把它作爲event data

for (var i in plugin.buttons) { 
    var button = plugin.buttons[i]; 
    var icon = button.icon; 
    var text = button.text; 
    var shortcut = button.shortcut; 
    var action = button.action; //action is a function (or method) 

    if (shortcut != null && shortcut.length > 0) { 
     if ($.isFunction(action)) { 

      $('div[contenteditable]').on('keydown', {shortcut : shortcut}, function (e) { 

       console.log(e.data.shortcut); 

      }); 
     } 
    } 
} 

但是在這種情況下，真正的問題是在for循環中沒有特殊的作用域，因此在for循環中定義變量只是在每次迭代時覆蓋相同的變量，這就是爲什麼當事件處理程序將在稍後調用。

你必須在變量鎖定在一個新的範圍

for (var key in plugin.buttons) { 
    (function(i) { 
     var button = plugin.buttons[i]; 
     var icon = button.icon; 
     var text = button.text; 
     var shortcut = button.shortcut; 
     var action = button.action; //action is a function (or method) 

     if (shortcut != null && shortcut.length > 0) { 
      if ($.isFunction(action)) { 
       console.log(shortcut); //it's valid shortcut 
       //using jQuery hotkey plugin 
       $('div[contenteditable]').bind('keydown', shortcut, function() { 
        console.log(shortcut); //it's undefined 
        action.call(); //it's undefined also 
        return false; 
       }); 
      } 
     } 
    })(key); 
}