JavaScript对象的动态属性？ [英] Dynamic Property of JavaScript object?

问题描述

我想知道如果这是可能的JavaScript，我想要一个可以包含动态属性的对象。

举个例子：

  function MyObject（）
 {
} 
 
 var myobj = new MyObject（）; 
 myobj.property1 =something; 
 
 alert（myobj.property1）; // something 
 alert（myobj.property2）; //这不应该报告错误，而是应该将属性评估为null，因为它从未被设置。 
  

有没有办法拦截JavaScript中的属性调用，所以我可以主动设置一个无值属性为空值？

谢谢。

解决方案

代码：

  var obj = {}; 
 alert（prop：+ obj.prop）; 
 obj.prop =something; 
 alert（prop：+ obj.prop）; 
删除obj.prop; 
 alert（prop：+ obj.prop）; 
  

行为：

 
警报：prop：undefined
警报：prop：something
警报：prop：undefined
 

I am wondering if this is possible in JavaScript, I want to have an Object which could contain dynamic properties.

Give an example:

function MyObject()
{
}

var myobj = new MyObject();
myobj.property1 = "something";

alert(myobj.property1); // something
alert(myobj.property2); // this should never report error, instead the property should be evaluated to null, as it has never been set. 

Is there any way to intercept property calls in JavaScript so I can proactively set a no-value property as null?

Thanks.

解决方案

This is about as close as you can get to achieving your goal.

Code:

var obj = {};
alert("prop: " + obj.prop);
obj.prop = "something";
alert("prop: " + obj.prop);
delete obj.prop;
alert("prop: " + obj.prop);

Behavior:

Alert: "prop: undefined"
Alert: "prop: something"
Alert: "prop: undefined"

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