CommonJS modules enables you to include javascript modules within the current scope and effectively keeps the global scope from being polluted.

This massively reduces the chance of naming collisions and keeps code organised.

That said I think it&#39;s pretty safe to say that AMD modules have now become more popular than CommonJS.

The RequireJS website has a very good section on [why to use modules](http://requirejs.org/docs/whyamd.html) and the differences between CommonJS and AMD.


I am using Entity Framework 5 (`DBContext`) and I am trying to find the best way to deep copy an entity (i.e. copy the entity and all related objects) and then save the new entities in the database. How can I do this? I have looked into using extension methods such as `CloneHelper` but I am not sure if it applies to `DBContext`.

Entity Framework 5 deep copy/clone of an entity

I&#39;m currently working on an application built with Express (Node.js) and I want to know what is the smartest way to handle different robots.txt for different environments (development, production).

This is what I have right now but I&#39;m not convinced by the solution, I think it is dirty:

    app.get &#39;/robots.txt&#39;, (req, res) -&gt;
      res.set &#39;Content-Type&#39;, &#39;text/plain&#39;
      if app.settings.env == &#39;production&#39;
        res.send &#39;User-agent: *\nDisallow: /signin\nDisallow: /signup\nDisallow: /signout\nSitemap: /sitemap.xml&#39;
      else
        res.send &#39;User-agent: *\nDisallow: /&#39;

(NB: it is CoffeeScript)

There should be a better way. How would you do it?

Thank you.

What is the smartest way to handle robots.txt in Express?

I&#39;m learning JS and someone more experienced mentioned that they use CommonJS to handle keeping js code organized (since there&#39;s no &quot;module&quot; functionality).

I looked on Quora, but it explained the *group* and it&#39;s goals, not so much how I might use it.



What is CommonJS and why should I care how it can help in writing .js applications?

I'm learning JS and someone more experienced mentioned that they use CommonJS to handle keeping js code organized (since there's no "module" functionality).
I looked on Quora, but it explained the group and it's goals, not so much how I might use it.

Assuming I have the following:

    var array = 
        [
            {&quot;name&quot;:&quot;Joe&quot;, &quot;age&quot;:17}, 
            {&quot;name&quot;:&quot;Bob&quot;, &quot;age&quot;:17}, 
            {&quot;name&quot;:&quot;Carl&quot;, &quot;age&quot;: 35}
        ]

What is the best way to be able to get an array of all of the distinct ages such that I get an result array of:

    [17, 35]

Is there some way I could alternatively structure the data or better method such that I would not have to iterate through each array checking the value of &quot;age&quot; and check against another array for its existence, and add it if not?

If there was some way I could just pull out the distinct ages without iterating...

Current inefficent way I would like to improve... If it means that instead of &quot;array&quot; being an array of objects, but a &quot;map&quot; of objects with some unique key (i.e. &quot;1,2,3&quot;) that would be okay too. Im just looking for the most performance efficient way.

The following is how I currently do it, but for me, iteration appears to just be crummy for efficiency even though it does work...

    var distinct = []
    for (var i = 0; i &lt; array.length; i++)
       if (array[i].age not in distinct)
          distinct.push(array[i].age)

How to get distinct values from an array of objects in JavaScript?

I was wondering what the **= +_** operator means in JavaScript.  It looks like it does assignments.

Example:

    hexbin.radius = function(_) {
       if (!arguments.length)
           return r;
       r = +_;
       dx = r * 2 * Math.sin(Math.PI / 3);
       dy = r * 1.5;
       return hexbin;
    };

What does = +_ mean in JavaScript

    formatCalendarDate = function (dateTime) {
        return moment.utc(dateTime).format(&#39;LLL&#39;);
    };

It displays: &quot;28 februari 2013 09:24&quot;

But I would like to remove the time at the end. How can I do that?

I&#39;m using [Moment.js][1].

  [1]: http://momentjs.com/

How can I remove time from date with Moment.js?

I have a string :

    var str = &quot;123, 124, 234,252&quot;;

I want to parse each item after split and increment 1. So I will have:

    var arr = [124, 125, 235, 253 ];

How can I do that in NodeJS?

How to split and modify a string in NodeJS?

I am currently using underscorejs for sort my json sorting. Now I have asked to do an `ascending` and `descending` sorting using underscore.js. I do not see anything regarding the same in the documentation. How can I achieve this? 

How can I do an asc and desc sort using underscore.js?

On this page ([http://docs.nodejitsu.com/articles/getting-started/what-is-require](https://web.archive.org/web/20130930091238/http://docs.nodejitsu.com/articles/getting-started/what-is-require)), it states that &quot;If you want to set the exports object to a function or a new object, you have to use the module.exports object.&quot;

My question is why.

    // right
    module.exports = function () {
      console.log(&quot;hello world&quot;)
    }
    // wrong
    exports = function () {
      console.log(&quot;hello world&quot;)
    }

I console.logged the result (`result=require(example.js)`) and the first one is `[Function]` the second one is `{}`.

Could you please explain the reason behind it? I read the post here: https://stackoverflow.com/questions/7137397/module-exports-vs-exports-in-nodejs . It is helpful, but does not explain the reason why it is designed in that way. Will there be a problem if the reference of exports be returned directly?

Difference between &quot;module.exports&quot; and &quot;exports&quot; in the CommonJs Module System

I&#39;m still very confused about **CommonJS, AMD** and **RequireJS**, even after reading a lot.

I know that **CommonJS** (formerly **ServerJS**) is a group for defining some **JavaScript** specifications (i.e. modules) when the language is used outside the browser. **CommonJS** modules specification has some implementation like **Node.js** or **RingoJS**, right?

&gt; What&#39;s the relation between **CommonJS**, **Asynchronous Module Definition** (AMD) and **RequireJS**? 
&gt;
&gt; Is **RequireJS** an implementation of the **CommonJS** module definition? If yes, what&#39;s **AMD** then?

Relation between CommonJS, AMD and RequireJS?

According to the Node.js manual:

&gt; If you want the root of your module&#39;s export to be a function (such as
&gt; a constructor) or if you want to export a complete object in one
&gt; assignment instead of building it one property at a time, assign it to
&gt; module.exports instead of exports.

The example given is:

    // file: square.js
    module.exports = function(width) {
      return {
        area: function() {
          return width * width;
        }
      };
    }

and used like this:

    var square = require(&#39;./square.js&#39;);
    var mySquare = square(2);
    console.log(&#39;The area of my square is &#39; + mySquare.area());

My question: why does the example not use square as an object? Is the following valid and does it make the example more &quot;object oriented&quot;?

    var Square = require(&#39;./square.js&#39;);
    var mySquare = new Square(2);
    console.log(&#39;The area of my square is &#39; + mySquare.area());
 

Node.js - use of module.exports as a constructor

I’m trying out webpack (http://webpack.github.io/) and it looks really nice, however I’m kind of stuck here.

Say that I’m using a CDN for a library, f.ex jQuery. Then in my code, I want the `require(&#39;jquery&#39;)` to automatically point to the global jquery instance, instead of trying to include it from my modules.

I’ve tried using plugins like the `IgnorePlugin`:

    new webpack.IgnorePlugin(new RegExp(&quot;^(jquery|react)$&quot;))

This works for ignoring the library, but it still says that the required module is &quot;missing&quot; when I run the webpacker.

Somehow I need to tell webpack that `jquery` should be picked up from the global context instead. Seems like a common use case, so I’m kind of surprised that the docs doesn’t target this specifically.

Webpack and external libraries

So the code is simple:

calls.json
   
    {&quot;SERVER&quot;:{
        &quot;requests&quot;:{
          &quot;one&quot;:&quot;1&quot;
        }
    } }

file.ts

    import json = require(&#39;../static/calls.json&#39;);
    console.log(json.SERVER);

the generated javascript is correct and when running the node js server, the console log json.SERVER prints &#39;{ requests: { one: &#39;1&#39; } }&#39;, as it should.

The typescript compiler (commonjs) however, somehow does not particularly like this situation and throws: &quot;Cannot find module &#39;../static/calls.json&#39;&quot;.

Ofcourse I tried writing a .d.ts file, like this:

    declare module &#39;../static/calls.json&#39;{
        var exp:any;
        export = exp;
    }

this then obviously throws: &quot;Ambient module declaration cannot specify relative module name&quot;.

I also tried different variants, like:

    declare module &#39;calls.json&#39; {
        import * as json from &#39;/private/static/calls.json&#39;;
        export = json;
    }
and then requiring:

    import json = require(&#39;calls.json&#39;);

None work properly and have their own little compiler errors :)

I want to use an external .json file because I use commonjs serverside and amd clientside and I want a single file for loading constants.

Content Type	Original Author	Original Content on Stackoverflow
Question	Clay Nichols	View Question on Stackoverflow
Solution 1 - Javascript	RayViljoen	View Answer on Stackoverflow

What is CommonJS and why should I care how it can help in writing .js applications?

Javascript Problem Overview

Javascript Solutions

Solution 1 - Javascript

What is the smartest way to handle robots.txt in Express?

Entity Framework 5 deep copy/clone of an entity

Attributions