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