什么时候应该在JavaScript中使用delete vs设置元素为null？ [英] When should I use delete vs setting elements to null in JavaScript?

问题描述

可能存在重复：

在JavaScript中删除对象

我有一个拥有大量属性的JS对象。如果我想强制浏览器垃圾收集这个对象，我是否需要将这些属性中的每一个都设置为null，或者是否需要使用delete操作符？两者有什么区别？

I have a JS object having a large number of properties. If I want to force the browser to garbage collect this object, do I need to set each of these properties as null or do I need to use the delete operator? What's the difference between the two?

推荐答案

JavaScript没有办法强制垃圾收集，而且你并不需要。 xy = null; 和删除xy; 都会消除 x 对前$ y 值的引用。必要时，该值将被垃圾回收。

There is no way to force garbage collection in JavaScript, and you don't really need to. x.y = null; and delete x.y; both eliminate x's reference to the former value of y. The value will be garbage collected when necessary.

如果你清空某个属性，它仍然被视为设置在对象上并且将被枚举。 / strong>我只能想到你更喜欢 delete 的地方是，如果你想枚举 x 。

If you null out a property, it is still considered 'set' on the object and will be enumerated. The only time I can think of where you would prefer delete is if you were going to enumerate over the properties of x.

考虑以下几点：

Consider the following:

var foo = { 'a': 1, 'b': 2, 'c': 3 };

console.log('Deleted a.');
delete foo.a
for (var key in foo)
  console.log(key + ': ' + foo[key]);

console.log('Nulled out b.');
foo['b'] = null;
for (var key in foo)
  console.log(key + ': ' + foo[key]);

此代码将产生以下输出：

This code will produce the following output:

Deleted a.
b: 2
c: 3
Nulled out b.
b: null
c: 3

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