在JavaScript中捕获对未定义属性的访问权限 [英] Catch access to undefined property in JavaScript

问题描述

Spider-Monkey JavaScript引擎实现JavaScript对象的 __ noSuchMethod __ 回调函数。

The Spider-Monkey JavaScript engine implements the __noSuchMethod__ callback function for JavaScript Objects.

此函数被调用每当JavaScript尝试执行Object的未定义方法时。

This function is called whenever JavaScript tries to execute an undefined method of an Object.

我想设置一个Object的回调函数，只要Object中的未定义属性被调用访问或分配给。

I would like to set a callback function to an Object that will be called whenever an undefined property in the Object is accessed or assigned to.

我还没有找到为JavaScript对象实现的 __ noSuchProperty __ 函数，我很好奇有任何解决方法可以达到相同的结果。

I haven't found a __noSuchProperty__ function implemented for JavaScript Objects and I am curios if there is any workaround that will achieve the same result.

请考虑以下代码：

var a = {};
a.__defineGetter__("bla", function(){alert(1);return 2;});
alert(a.bla);

相当于 [alert（1）; alert（2）] - 即使a.bla未定义。

It is equivalent to [alert(1);alert(2)] - even though a.bla is undefined.

我想获得相同的结果但是未知属性（即事先不知道a。bla将是访问的属性）

I would like to achieve the same result but to unknown properties (i.e. without knowing in advance that a."bla" will be the property accessed)

推荐答案

在ECMAScript的下一个版本中，它应该非常简单，使用Object.observe 。
在此处阅读更多内容：
http： //addyosmani.com/blog/a-few-new-things-coming-to-javascript/

In ECMAScript's next version it should be quite easy, using Object.observe. Read more here: http://addyosmani.com/blog/a-few-new-things-coming-to-javascript/

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