拆除 JavaScript 中的闭包

发布于 2024-09-24 00:00:29 字数 238 浏览 2 评论 0原文

有没有办法在 JavaScript 中拆掉闭包来确定函数是什么以及作用域是什么？

或者，也许更简洁，有没有办法在 JavaScript 中序列化闭包？

编辑

如果给我一个声明如下的函数，我想知道什么：

var o = {};
var f = function() { return o; }

有没有办法只查看 f 并找到 o？

原文

is there a way to tear down a closure in JavaScript to determine what the function is and what the scope is?

Or, maybe more succinctly, is there a way to serialize a closure in JavaScript?

edit

What I am wondering if I am given a function declared as follows:

var o = {};
var f = function() { return o; }

Is there a way to look at just f and find o?

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土豪我们做朋友吧 2024-10-01 00:00:29

我不确定你所说的“拆除封闭”是什么意思。可以使用arguments.callee来确定函数是什么：

function test () { console.log(arguments.callee); }
// -> function test () { console.log(arguments.callee); }

范围是什么？

检查变量是否在作用域内的唯一真正方法是尝试访问它。这意味着您需要使用 try/catch 语句，因为如果您引用未声明的变量，则会引发错误：

try{ myVar; alert("myVar is in scope"); }catch (e){ alert("myVar is not in scope"); }

实际上，如果您编写了代码，或者甚至通过检查代码（如果您不这样做），您就已经知道哪些变量在范围内。不写它。

如果您尝试获取堆栈，您可以（某种程度上）使用caller属性~~来执行此操作，但它是非标准的，并且可能不适用于所有 JS 实现~~^*：

function getStack () {
    var stack = [], cFunc = arguments.callee;
    while (cFunc = cFunc.caller)
        stack.push(cFunc);

    console.dir(stack);
}

function func1 () { func2(); }
function func2 () { try { obviousError(); } catch (e) { getStack(); } }

大多数内置开发人员工具都会以更清晰的方式为您提供堆栈（IE 7 和 IE 8 没有），因此最好尽可能使用它们。

^{* 目前所有主流浏览器都支持Function.caller。它似乎也是在 ECMAScript 3.1 中定义的 - 您可以在此处查看支持.}

I'm not sure what you mean by "tear down a closure". Determining what the function is can be done using arguments.callee:

function test () { console.log(arguments.callee); }
// -> function test () { console.log(arguments.callee); }

and what the scope is?

The only real way to check to see if a variable is in scope is by trying to access it. That means you need to use a try/catch statement, because an error is thrown if you refer to an undeclared variable:

try{ myVar; alert("myVar is in scope"); }catch (e){ alert("myVar is not in scope"); }

Realistically you would already know which variables are in scope if you wrote the code or even by examining the code if you didn't write it.

If you're trying to get the stack, you can (sort of) do this using the caller property~~, but it's non-standard and might not be available in all JS implementations~~^*:

function getStack () {
    var stack = [], cFunc = arguments.callee;
    while (cFunc = cFunc.caller)
        stack.push(cFunc);

    console.dir(stack);
}

function func1 () { func2(); }
function func2 () { try { obviousError(); } catch (e) { getStack(); } }

Most built-in developer tools give you the stack (IE 7 and IE 8 don't) in a much clearer manner, so it's best to use them where possible.

^{* Currently all major browsers support Function.caller. It also appears that it is defined in ECMAScript 3.1 - you can check support here.}

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