垃圾回收和JavaScript“删除":这是过分的/混淆性还是好的做法? [英] Garbage Collection and JavaScript "delete": Is this overkill/obfuscation, or a good practice?

问题描述

我刚刚阅读了这个问题和可接受的答案:什么是JavaScript垃圾回收?

I just read this question and the accepted answer: What is JavaScript garbage collection?

在回答中， Noldorin 引用了Apple的一些准则.这是我关心的部分:

In the answer, Noldorin referenced some guidelines from Apple. Here is the part I'm concerned with:

使用删除语句.每当使用新语句创建对象时，将其与delete语句配对.这样可以确保与对象关联的所有内存(包括其属性名称)都可用于垃圾回收.

Use delete statements. Whenever you create an object using a new statement, pair it with a delete statement. This ensures that all of the memory associated with the object, including its property name, is available for garbage collection.

我总是花时间跟上最佳实践的步伐，尤其是在我可以减少脚本的内存占用的情况下.所以我去测试一些东西.如果我理解正确，下面是一个对象的示例，该对象在调用方法后会自行删除.

I'm always taking time to keep up-to-speed on best practices, especially if I can reduce the memory footprint of my scripts. So I went off to test some things. If I understand correctly, the following is an example of an object that deletes itself after invoking a method.

var thing = function () {
    var a_method, and_another;
    a_method    = function() { /* do stuff */ };
    and_another = function() { /* do some other stuff*/ };
    this.init   = function() { a_method(); and_another(); };
};
delete new thing().init();

通常，我将所有内容包装在一个自调用函数中，并像上面那样传递我的全局变量.一切都和我通常做的一样，唯一的不同是我在new之前添加了delete.

Usually I'll wrap everything in a self invoking function and pass in my globals just like above. Everything is the same as I would normally do it, the only difference being that I added the delete right before the new.

代码以任何一种方式起作用.

The code works either way.

所以问题是:我在这里做什么 吗?删除对仅存在于功能范围内的对象的引用是否有某种好处?还是我只是让事情看起来混乱?

So the question is: Am I doing anything here? Is there some kind of benefit to deleting a reference to an object that only exists inside a function scope? Or am I just making things look confusing?

推荐答案

首先，语句delete new scoped_object().init();并没有真正做任何事情，您最好注意哪些变量仍处于封闭状态，或者如果您有循环引用，这是内存泄漏的最常见来源.

First of all the statement delete new scoped_object().init(); is not really doing anything, you should better take care about what variables remain in-closure or if you have circular references, which are the most common source of memory leaks.

delete运算符用于删除对象属性，并且确实被误解了，您从@Noldorin引用的答案引用了一些 Apple JavaScript最佳做法" ，但是他们对delete的工作原理一无所知.

The delete operator is meant to be used to delete object properties, and it is really misunderstood, the answer you quote from @Noldorin quotes some text of the Apple JavaScript "Best Practices", but they don't have a clue about how delete works!!.

他们甚至建议在变量引用上使用delete，这是不可能的-仅适用于在 Eval Code 中声明的变量，因为var语句将变量声明为不可删除(在ECMAScript 3中为{DontDelete}，在ECMAScript 5中为[[Configurable]] = false)的可变对象-构成作用域链的对象的属性.

They even recommend using delete on variable references, and that is not possible -only possible for variables declared in Eval Code-, because the var statement declares the variable as non-deletable ({DontDelete} in ECMAScript 3, or [[Configurable]] = false in ECMAScript 5) properties of the Variable Object -objects that form the scope chain-.

此外，尝试delete引用绑定到环境记录的标识符-用VariableDeclaration，FunctionDeclaration或从函数的FormalParameterList-声明的标识符，会导致SyntaxError异常在新的 ECMAScript 5th Edition 下的

Moreover, attempting to delete a reference to an identifier that is bound to an environment record - an identifier declared with a VariableDeclaration, FunctionDeclaration or from a function's FormalParameterList-, causes a SyntaxError exception on the new ECMAScript 5th Edition under Strict Mode.

我建议您阅读以下有关delete的文章:

I would recommend you to read the following article about delete:

• 了解delete

这篇关于垃圾回收和JavaScript“删除":这是过分的/混淆性还是好的做法?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！