nodejs 模块中的全局对象是什么? [英] What's the global object within a module in nodejs?

问题描述

我知道在 node 中，每个模块都有一个局部作用域，并且在一个模块中定义的变量不会转义到全局，除非明确导出.

I know in node, every module gets an local scope and variable defined within one module won't escape to the global unless explicitly exported.

我想知道的是，当我在一个模块文件中如下声明一个变量时，这个变量定义的全局对象是什么?

What I want to know is when I declare a variable in one module file as the following, what's the global object this variable defined on?

var obj = {};
// In browser, this is defined on window.obj
// How about in the node?

有一个声明，global 是用作局部全局作用域的对象，但是以下测试代码失败:

There is one statement that global is the object used as the local global scope, however the following test code fails:

a = 1
console.log global.a
// undefined

那么什么是模块的全局变量?

So what is the global variable for a module?

推荐答案

node里面其实有一个全局对象；它简称为global.您可以为它分配属性并像访问任何其他对象一样访问这些属性，并且可以跨模块执行此操作.然而，直接访问它(global.foo=bar 在一个模块中，baz=global.foo 在另一个模块中)是唯一访问方式它.非限定变量名永远自动解析为其属性，例如，浏览器环境中的非限定变量名解析为window.somethingOrOther.在 node 中，每个模块在概念上都包含在一个立即函数调用中，因此非限定名称代表局部变量并具有模块级作用域.

There is in fact a global object in node; it's simply called global. You can assign properties to it and access those properties just like any other object, and you can do it across modules. However, directly accessing it (global.foo=bar in one module, baz=global.foo in another) is the only way to access it. Unqualified variable names never automatically resolve to its properties the way that, say, an unqualified variable name in a browser environment would resolve to window.somethingOrOther. In node, every module is conceptually wrapped inside an immediate function call, so unqualified names represent local variables and have module-level scope.

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