在对象上设置属性时调用函数 [英] Call a function when a property gets set on an object

问题描述

我真的不知道怎么解释这个，但我会告诉你代码并告诉你我想要实现的目标。

I don't really know how to explain this but I'll show you code and tell you what I'd like to achieve.

假设我说快速对象：

var test = {};

然后我为它设置了一个属性:(我坚持语法，它不能使用任何函数作为setter）

And then I set a property to it: (I insist on the syntax, it mustn't use any function as the setter)

test.hello = 'world';

非常简单，是吗？现在我想向该对象添加一个函数，每次设置一个新属性时都会调用该函数。像这样：

Pretty simple, eh? Now I'd like to add a function to that object that would get called everytime a new property gets set. Like this:

var test = { 
                newPropertyHasBeenSet: function(name){ 
                    console.log(name + 'has been set.'); 
                } 
            };

test.hello = 'world';

// Now newPropertyHasBeenSet gets called with 'hello' as an argument.
// hello has been set.

我不知道是否可能，但这将是非常惊人的。任何人都知道如何实现这一目标？

I don't know if it's possible, but that would be quite amazing. Anyone has an idea of how to achieve so?

编辑：我也希望能够为财产获取做同样的事情（所以 test.hello 会调用 get（'hello'）例如。）

I'd like also to be able to do the same for property get (so test.hello would call get('hello') for example).

EDIT2：这是针对使用node.js的服务器端javascript 。

非常感谢，祝你有愉快的一天！

Thanks a lot and have a nice day!

推荐答案

在chrome中尝试此示例（如之前的评论所述，它使用 ES6代理）：

try this example in chrome (as mentioned in previous comments it uses ES6 Proxy):

var p = Proxy.create({
  get: function(proxy, name) {
    console.log('read request to ' + name + ' property');
    if (name=="test_test")
       return 1234;
    else
       return "Meh";
  },
  set: function(proxy, name, value) {
    console.log('write request to ' + name + ' property with ' + value + ' value');
  }
});

console.log(p.test_test);
console.log(p.test)
p.qqq = "test";

结果：

read request to test_test property
1234
read request to test property
Meh
write request to qqq property with test value

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