null和undefined对于显式使对象不可访问是否有效? [英] Are null and undefined equally valid for explicitly making objects unreachable?
问题描述
根据有关相关问题的答案,如果希望它们成为对象,则最好使其明确不可用垃圾收集.
出于所有实际意图和目的,用null
值还是undefined
值完成是否重要?
According to this answer on a related question, it's best to make an object explicitly unavailable if you want them to be garbage-collected.
For all practical intents and purposes, does it matter whether that's done with a null
value or an undefined
value?
简而言之,垃圾收集器是否可以平等地访问以下两个对象(无论它们最初引用了什么)?
Shortly put, will both of the below objects (whatever they may have referenced originally) be equally accessible for the garbage collector?
window.foo = null;
window.bar = void 0;
推荐答案
分配的值并不重要:它可能是null
,undefined
,{}
或42
.
It does not matter what value you assign: it might be null
, undefined
, {}
or 42
.
重要的是,您需要断开变量和堆中对象之间的连接.
What matters is that you need to break the connection between a variable and an object in heap.
一旦某个对象不可访问,它就是要被收集的候选对象,而不论一天中引用该对象的变量当前具有什么当前值.
As soon as an object is not reachable - it's a candidate for being collected, regardless on what the current value the variable that referred to it one day currently holds.
这是一个来自Google Chrome浏览器的内存快照,仅供参考:
Here is a memory snapshots from a Google Chrome, just for fun:
以及相应的JSFiddle: http://jsfiddle.net/r9b5taxf/
And the corresponding JSFiddle: http://jsfiddle.net/r9b5taxf/
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