blocks|key|3177843|text|更具体地说：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3177844|module是文件中的全局作用域变量。|offset|length|style|CODE|3177845|因此，如果您调用require("foo")，那么：|3177846|//+foo.js
console.log(this+===+module);+//+true|code-block|syntax|javascript|3177847|它的工作方式与window在浏览器中的工作方式相同。|3177848|还有另一个名为global的全局对象，您可以在任何想要的文件中对其进行读写，但这涉及到改变全局范围，这就是EVIL|BOLD|3177849|exports是一个存在于module.exports上的变量。它基本上就是您在需要文件时导出的内容。|3177850|//+foo.js
module.exports+=+42;

//+main.js
console.log(require("foo")+===+42);+//+true|3177851|exports本身有一个小问题。_global作用域context%2B和module不是同一个。(在浏览器中，全局范围上下文和window是相同的)。|3177852|//+foo.js
var+exports+=+{};+//+creates+a+new+local+variable+called+exports,+and+conflicts+with

//+living+on+module.exports
exports+=+{};+//+does+the+same+as+above
module.exports+=+{};+//+just+works+because+its+the+"correct"+exports

//+bar.js
exports.foo+=+42;+//+this+does+not+create+a+new+exports+variable+so+it+just+works|3177853|Read+more+about+exports|3177854|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/5311334/what-is-the-purpose-of-nodejs-module-exports-and-how-do-you-use-it^0|0|0|6|0|8|E|0|0|7|6|0|7|6|1H|4|0|0|7|D|E|0|0|0|7|Z|6|1Q|6|1A|S|0|0|0|N|0|N|0|0^^$0|@$1|2|3|4|5|6|7|1B|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1C|8|@$D|1D|E|1E|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|1F|8|@$D|1G|E|1H|F|G]]|9|@]|A|$]]|$1|J|3|K|5|L|7|1I|8|@]|9|@]|A|$M|N]]|$1|O|3|P|5|6|7|1J|8|@$D|1K|E|1L|F|G]]|9|@]|A|$]]|$1|Q|3|R|5|6|7|1M|8|@$D|1N|E|1O|F|G]|$D|1P|E|1Q|F|S]]|9|@]|A|$]]|$1|T|3|U|5|6|7|1R|8|@$D|1S|E|1T|F|G]|$D|1U|E|1V|F|G]]|9|@]|A|$]]|$1|V|3|W|5|L|7|1W|8|@]|9|@]|A|$M|N]]|$1|X|3|Y|5|6|7|1X|8|@$D|1Y|E|1Z|F|G]|$D|20|E|21|F|G]|$D|22|E|23|F|G]|$D|24|E|25|F|S]]|9|@]|A|$]]|$1|Z|3|10|5|L|7|26|8|@]|9|@]|A|$M|N]]|$1|11|3|12|5|6|7|27|8|@$D|28|E|29|F|S]]|9|@$D|2A|E|2B|1|2C]]|A|$]]|$1|13|3|-4|5|6|7|2D|8|@]|9|@]|A|$]]]|14|$15|$5|16|17|18|A|$19|1A]]]]

To be more specific:

<code>module</code> is the global scope variable inside a file.

So if you call <code>require("foo")</code> then :

<pre><code>// foo.js
console.log(this === module); // true
</code></pre>

It acts in the same way that <code>window</code> acts in the browser. 

There is also another global object called <code>global</code> which you can write and read from in any file you want, but that involves mutating global scope and this is EVIL

<code>exports</code> is a variable that lives on <code>module.exports</code>. It's basically what you export when a file is required.

<pre><code>// foo.js
module.exports = 42;

// main.js
console.log(require("foo") === 42); // true
</code></pre>

There is a minor problem with <code>exports</code> on it's own. The _global scope context+ and <code>module</code> are not the same. (In the browser the global scope context and <code>window</code> are the same).

<pre><code>// foo.js
var exports = {}; // creates a new local variable called exports, and conflicts with

// living on module.exports
exports = {}; // does the same as above
module.exports = {}; // just works because its the "correct" exports

// bar.js
exports.foo = 42; // this does not create a new exports variable so it just works
</code></pre>

<a href="https://stackoverflow.com/questions/5311334/what-is-the-purpose-of-nodejs-module-exports-and-how-do-you-use-it">Read more about exports</a>

blocks|key|3177871|text|模块是一个对象，表示该特定源文件希望公开的内容。您可以通过定义此对象来描述模块导出的内容，而不是类似于c/c%2B%2B世界中的头文件。然后，节点运行时使用此对象来确定模块的哪些内容是“公共的”。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3177872|它的概念类似于在编译世界中从dll中导出函数。你必须明确定义哪些函数可以被外部世界访问。这有助于封装，并让您以一种干净的方式组织您的库。|3177873|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

module is an object that represents what that particular source file would like to publicly expose. Instead of having something akin to header files in the c/c++ world, you describe what the module exports by defining this object. the node runtime then uses this object to determine what about your module is 'public.'

its a similar concept to exporting functions from a dll in the compiled world. you have to define explicitly what functions can be accessed by the outside world. this helps with encapsulation and lets your organize your libraries in a clean way.

blocks|key|268989|text|扩展一下Raynos的答案..。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|268990|exports基本上是一个用于module.exports的别名-我建议不要使用它。您可以通过在+module.exports，上设置来自模块的公开方法和属性，如下所示：|offset|length|style|CODE|BOLD|268991|//file+'module1.js'
module.exports.foo+=+function+()+{+return+'bar'+}
module.exports.baz+=+5|code-block|syntax|javascript|268992|然后你可以在你的代码中访问它：|268993|var+module1+=+require('module1')
console.log(module1.foo())
console.log(module1.baz)|268994|您还可以完全使用覆盖+module.exports，以便根据需要提供单个对象：|268995|//glorp.js
module.exports+=+function+()+{
++this.foo+=+function+()+{+return+'bar'+}
++this.baz+=+5
++return+this+//+need+to+return+`this`+object+here
}|268996|现在你已经有了一个很好的原型：|268997|var+g1+=+new+require('glorp')()
console.log(g1.foo())
console.log(g1.baz)|268998|使用module.exports和require的方式有很多种。请记住，require('foo')+总是返回相同的实例，即使您多次调用它。|268999|备注|269000|为了让下面的方法起作用，|269001|var+g1+=+new+require('glorp')()
console.log(g1.foo())
console.log(g1.baz)+|269002|在分配给module.exports的函数中必须返回this。否则，您将获得一个TypeError|269003|console.log(g1.foo())
++++++++++%5E
TypeError:+Cannot+read+property+'foo'+of+undefined|269004|entityMap^0|0|0|7|F|E|1D|E|U|2|1D|N|0|0|0|0|8|2|B|E|0|0|0|0|2|E|H|7|10|E|1F|9|0|0|0|0|4|E|Q|4|14|9|0|0^^$0|@$1|2|3|4|5|6|7|1D|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1E|8|@$D|1F|E|1G|F|G]|$D|1H|E|1I|F|G]|$D|1J|E|1K|F|G]|$D|1L|E|1M|F|H]|$D|1N|E|1O|F|H]]|9|@]|A|$]]|$1|I|3|J|5|K|7|1P|8|@]|9|@]|A|$L|M]]|$1|N|3|O|5|6|7|1Q|8|@]|9|@]|A|$]]|$1|P|3|Q|5|K|7|1R|8|@]|9|@]|A|$L|M]]|$1|R|3|S|5|6|7|1S|8|@$D|1T|E|1U|F|H]|$D|1V|E|1W|F|G]]|9|@]|A|$]]|$1|T|3|U|5|K|7|1X|8|@]|9|@]|A|$L|M]]|$1|V|3|W|5|6|7|1Y|8|@]|9|@]|A|$]]|$1|X|3|Y|5|K|7|1Z|8|@]|9|@]|A|$L|M]]|$1|Z|3|10|5|6|7|20|8|@$D|21|E|22|F|G]|$D|23|E|24|F|G]|$D|25|E|26|F|G]|$D|27|E|28|F|H]]|9|@]|A|$]]|$1|11|3|12|5|6|7|29|8|@]|9|@]|A|$]]|$1|13|3|14|5|6|7|2A|8|@]|9|@]|A|$]]|$1|15|3|16|5|K|7|2B|8|@]|9|@]|A|$L|M]]|$1|17|3|18|5|6|7|2C|8|@$D|2D|E|2E|F|G]|$D|2F|E|2G|F|G]|$D|2H|E|2I|F|G]]|9|@]|A|$]]|$1|19|3|1A|5|K|7|2J|8|@]|9|@]|A|$L|M]]|$1|1B|3|-4|5|6|7|2K|8|@]|9|@]|A|$]]]|1C|$]]

To expand on Raynos's answer...

<code>exports</code> is basically an alias for <code>module.exports</code> - I recommend just not using it. You can expose methods and properties from a module by setting them on <code>module.exports</code>, as follows:

<pre><code>//file 'module1.js'
module.exports.foo = function () { return 'bar' }
module.exports.baz = 5
</code></pre>

Then you get access to it in your code:

<pre><code>var module1 = require('module1')
console.log(module1.foo())
console.log(module1.baz)
</code></pre>

You can also override <code>module.exports</code> entirely to simply provide a single object upon require:

<pre><code>//glorp.js
module.exports = function () {
 this.foo = function () { return 'bar' }
 this.baz = 5
 return this // need to return `this` object here
}
</code></pre>

Now you've got a nice prototype:

<pre><code>var g1 = new require('glorp')()
console.log(g1.foo())
console.log(g1.baz)
</code></pre>

There are myriad other ways to play with <code>module.exports</code> and <code>require</code>. Just remember, <code>require('foo')</code> always returns the same instance even if you call it multiple times.

<h1>Note</h1>

For the following to work, 

<pre><code>var g1 = new require('glorp')()
console.log(g1.foo())
console.log(g1.baz) 
</code></pre>

<code>this</code> has to be returned in the function that is assigned to <code>module.exports</code>. Otherwise, you'll get a <code>TypeError</code>:

<pre><code>console.log(g1.foo())
 ^
TypeError: Cannot read property 'foo' of undefined
</code></pre>

blocks|key|270881|text|您可以在node.js源代码中找到最佳答案。如果有人需要你的js模块，你的脚本会按节点转换成一个函数，如下所示(参见src/node.js)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|270882|//+require+function+does+this..
(function+(exports,+require,+module,+__filename,+__dirname)+{
++++...+your+javascript+contents...
});|code-block|syntax|javascript|270883|节点将包装您的脚本。然后执行上述脚本，如下所示：|270884|//module.js
var+args+=+[self.exports,+require,+self,+filename,+dirname];
return+compiledWrapper.apply(self.exports,+args);|270885|所以在你的脚本中，|270886|exports+is+just+module.exports.|270887|在脚本中，您可以向该导出对象添加一些内容(函数..)。require函数将返回此对象。这是node.js的模块系统(commonJS规范)。|270888|但要注意不要修改module.exports。否则，您当前的导出将毫无意义。|270889|entityMap^0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|Y|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|10|8|@]|9|@]|A|$]]|$1|Q|3|R|5|6|7|11|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|T|$]]

You can find the best answer in node.js source code.
If someone is requiring your js module, 
your script turns into a function by node as follows (see src/node.js).

<pre><code>// require function does this..
(function (exports, require, module, __filename, __dirname) {
 ... your javascript contents...
});
</code></pre>

Node will wrap your script. Then above script will be executed as follows:

<pre><code>//module.js
var args = [self.exports, require, self, filename, dirname];
return compiledWrapper.apply(self.exports, args);
</code></pre>

So in your script, 

<pre><code>exports is just module.exports.
</code></pre>

In your script, you can add something to this exports object (functions..).
require function will return this object. This is node.js's module system (commonJS specification).

But be careful not to modify module.exports. Otherwise your current exports will be meaningless.

blocks|key|269022|text|模块的代码被包装在module.exports中(模块，可能由其他模块组成)。构建模块的方法有很多种，但这是一种非常常见的方法(也是我个人最喜欢的一种)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|269023|//+Dependencies
//+const+module+=+require('module');

//+Module+object
var+foo+=+{}

//+Internal+property
foo._a+=+'a';

//+"Public"+property
foo.b+=+'b';

//+Method
foo.fu+=+function()+{+return+'fu'+};

//+Export
module.exports+=+foo;|code-block|syntax|javascript|269024|entityMap^0|9|E|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

Module's code is wrapped in module.exports (The module, maybe composed by other module).
There are many ways to build a module, but this is one very common (and my personal favorite).

<pre><code>// Dependencies
// const module = require('module');

// Module object
var foo = {}

// Internal property
foo._a = 'a';

// "Public" property
foo.b = 'b';

// Method
foo.fu = function() { return 'fu' };

// Export
module.exports = foo;
</code></pre>

Looking at a random <a href="https://github.com/visionmedia/express/blob/master/lib/router/index.js">source file</a> of the <code>express</code> framework for <code>NodeJS</code>, there are two lines of the code that I do not understand (these lines of code are typical of almost all NodeJS files).

<pre><code>/**
 * Expose `Router` constructor.
 */

exports = module.exports = Router;
</code></pre>

and

<pre><code>/**
 * Expose HTTP methods.
 */

var methods = exports.methods = require('./methods');
</code></pre>

I understand that the first piece of code allows the rest of the functions in the file to be exposed to the NodeJS app, but I don't understand exactly how it works, or what the code in the line means. 

<blockquote>
 What do <code>exports</code> and <code>module.exports</code> actually mean?
</blockquote>

I believe the 2nd piece of code allows the functions in the file to access <code>methods</code>, but again, how exactly does it do this.

Basically, what are these magic words: <code>module</code> and <code>exports</code>?

What do "module.exports" and "exports.methods" mean in NodeJS / Express?

查看用于NodeJS的express框架的随机，有两行代码我不理解(这两行代码是几乎所有NodeJS文件的典型)。/** * Expose `Router` constructor. */exports = module.exports = Router;和/** * Expose HTTP methods. */va...

问"module.exports“和"exports.methods”在NodeJS / Express中是什么意思？
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问"module.exports“和"exports.methods”在NodeJS / Express中是什么意思？
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