javascript new 关键字和内存泄漏? [英] javascript new keyword and memory leaks?

问题描述

let x = new MyClass();
...[more code]
let x = new MyClass();

MyClass 的第一个实例会自动被垃圾回收吗?或者我是否需要在第二次赋值之前显式 x = null 或类似的东西，以避免内存泄漏?

Will the first instance of MyClass get garbaged collected automatically? Or do I need to explicitly x = null or something like that before the second assignment, in order to avoid a memory leak?

推荐答案

JavScript 的内存是自动管理的，因此被视为无法访问"的对象由 垃圾收集器.

JavScript's memory is managed automatically, so objects that are deemed "unreachable" are collected by the garbage collector.

在您提供的示例中，存储在 x 中的对象将被垃圾收集，只要它不能从您的代码的其他部分访问(即，如果您将它放在全局范围内...[more code] 行，对象不会被收集，因为它仍然可以访问).

In the example you provided, the object stored in x will be garbage-collected so long as it isn't reachable from other parts of your code (i.e. if you placed it in global scope in the ...[more code] lines, the object would not be collected as it is still reachable).

大多数情况下，您不必担心 JavaScript 中的显式内存管理，但是了解其重要的常见情况很重要(请参阅 4 种常见泄漏).

Most of the time, you don't have to worry about explicit memory management in JavaScript, however it is important to know common cases where it does matter (see 4 common leaks).

作为一个实际例子，在大多数前端框架/库中，销毁由应用程序的短期组件创建的 setInterval 很重要(即当倒计时时钟发生时销毁倒计时时钟的间隔)已从 DOM 中删除)，因为这些间隔中的闭包可能会阻止对象被收集.

As a practical example, in most front-end frameworks/libraries, it's important to destroy setIntervals created by short-lived components of your app (i.e. destroying a countdown clock's interval when that countdown clock has been removed from the DOM) as the closure in these intervals could prevent objects from being collected.

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