javascript defineProperty使属性不可枚举 [英] javascript defineProperty to make an attribute non enumerable

问题描述

我想使用defineProperty使属性不出现在循环中的...，但它不工作。

I'm trying to use defineProperty to made attributes not appear in for...in cycle, but it doesn't work. Is this code correct?

function Item() {
    this.enumerable = "enum";
    this.nonEnum = "noEnum";
}
Object.defineProperty(Item, "nonEnum", { enumerable: false });

var test = new Item();

for (var tmp in test){
    console.log(tmp);
}

推荐答案

项没有名为 nonEnum 的属性（检查出）。它是一个（构造函数）函数，它将创建一个具有 nonEnum 属性的对象。

Item does not have a property named nonEnum (check it out). It is a (constructor) function that will create an object that has a property called nonEnum.

将工作：

var test = new Item();
Object.defineProperty(test, "nonEnum", { enumerable: false });

您也可以这样写：

function Item() {
    this.enumerable = "enum";
    Object.defineProperty(this, "nonEnum", { 
        enumerable: false, 
        value: 'noEnum' 
    });
}

jsFiddle演示

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