Here is how you can read the entire file contents, and if done successfully, start a webserver which displays the JPG image in response to every request:

&lt;!-- language: lang-javascript --&gt;

    var http = require(&#39;http&#39;)
    var fs = require(&#39;fs&#39;)

    fs.readFile(&#39;image.jpg&#39;, function(err, data) {
      if (err) throw err // Fail if the file can&#39;t be read.
      http.createServer(function(req, res) {
        res.writeHead(200, {&#39;Content-Type&#39;: &#39;image/jpeg&#39;})
        res.end(data) // Send the file data to the browser.
      }).listen(8124)
      console.log(&#39;Server running at http://localhost:8124/&#39;)
    })

Note that the server is launched by the &quot;readFile&quot; callback function and the response header has `Content-Type: image/jpeg`.

**[Edit]** You could even embed the image in an HTML page directly by using an `&lt;img&gt;` with a [data URI source](http://en.wikipedia.org/wiki/Data_URI_scheme). For example:

&lt;!-- language: lang-javascript --&gt;

      res.writeHead(200, {&#39;Content-Type&#39;: &#39;text/html&#39;});
      res.write(&#39;&lt;html&gt;&lt;body&gt;&lt;img src=&quot;data:image/jpeg;base64,&#39;)
      res.write(Buffer.from(data).toString(&#39;base64&#39;));
      res.end(&#39;&quot;/&gt;&lt;/body&gt;&lt;/html&gt;&#39;);


Two things to keep in mind **Content-Type** and the **Encoding**

1) What if the file is css

    if (/.(css)$/.test(path)) {
      res.writeHead(200, {&#39;Content-Type&#39;: &#39;text/css&#39;});	
      res.write(data, &#39;utf8&#39;);
    } 

2) What if the file is jpg/png

    if (/.(jpg)$/.test(path)) {
      res.writeHead(200, {&#39;Content-Type&#39;: &#39;image/jpg&#39;});
      res.end(data,&#39;Base64&#39;);
    }


Above one is just a sample code to explain the answer and not the exact code pattern.

Suppose that I have a string in scala and I want to try to parse a double out of it.  

I know that, I can just call `toDouble` and then catch the java num format exception if this fails, but is there a cleaner way to do this?  For example if there was a `parseDouble` function that returned `Option[Double]` this would qualify.  

I don&#39;t want to put this in my own code if it already exists in the standard library and I am just looking for it in the wrong place.

Thanks for any help you can provide.

How to find if a Scala String is parseable as a Double or not?

EDIT: I keep getting upvotes here. Just for the record, I no longer think this is important. I haven&#39;t needed it since I posted it.

I would like to do following in Scala ...

    def save(srcPath: String, destPath: String) {
        if (!destPath.endsWith(&#39;/&#39;))
            destPath += &#39;/&#39;
        // do something
    }

... but I can&#39;t beacuse `destPath` is a val. Is there any way to declare `destPath` as var?

Note: there are similar questions but in all of them OP just wanted to modify array.

Please do not advise following:

&gt; Mutating the input parameters is often seen as bad style and makes it
&gt; harder to reason about code.

I think it&#39;s valid in imperative programming (Scala allows both, right?) and adding something like `tmpDestPath` would just add clutter.

EDIT: Don&#39;t misunderstand. I know that strings aren&#39;t mutable and I don&#39;t want a reference to reference because I don&#39;t want to modify data of caller. I just want to modify local reference to string that caller gave me with my string (eg. orig + &#39;/&#39;). I want to modify that value only in scope of current method. Look, this is perfectly valid in Java:

    void printPlusOne(int i) {
        i++;
        System.out.println(&quot;i is: &quot; + i);
        System.out.println(&quot;and now it&#39;s same: &quot; + i);
    }

I don&#39;t have to create new variable and i don&#39;t have to compute i+1 twice.

Scala - mutable (var) method parameter reference

I&#39;ve been trying to find an example of how to read a jpeg image and then show the image.

    var http = require(&#39;http&#39;), fs = require(&#39;fs&#39;);

    http.createServer(function (req, res) {
        res.writeHead(200, {&#39;Content-Type&#39;: &#39;text/html&#39;});

	fs.readFile(&#39;image.jpg&#39;, function (err, data) {
	  if (err) throw err;
	  res.write(data);
	});

	res.end();
    }).listen(8124, &quot;127.0.0.1&quot;);
    console.log(&#39;Server running at http://127.0.0.1:8124/&#39;);

Tried the following code but I think the encoding needs to be set as buffer. Using console.log it outputs &#39;Object&#39; for the data.

nodejs - How to read and output jpg image?

I've been trying to find an example of how to read a jpeg image and then show the image.
<pre><code class="hljs language-javascript">var http = require('http'), fs = require('fs');

http.createServer(function (req, res) {
 res.writeHead(200, {'Content-Type': 'text/html'});

fs.readFile('image.jpg', function (err, data) {
 if (err) throw err;
 res.write(data);
});

res.end();
}).listen(8124, "127.0.0.1");
console.log('Server running at http://127.0.0.1:8124/');
</code></pre>
Tried the following code but I think the encoding needs to be set as buffer. Using console.log it outputs 'Object' for the data.

I&#39;m pretty confused with the use of the `select` method. This is how I use it, and it&#39;s wrong:

    Transaction.find({username : user.username}).select(&#39;uniqueId&#39;, &#39;confirmation_link&#39;, &#39;item_name&#39;, &#39;timeout&#39;, &#39;username&#39;, function(err, txs){
    		callback(txs);
    });

What I&#39;m trying to achieve is simply to select from the transactions in the database the ones with that username and I want to take out just the fields listed in the `select` method. Can anyone point out how should I use the `select` method? Thanks.

Mongoose use of .select() method

How can I make an HTTP request from within Node.js or Express.js? I need to connect to another service. I am hoping the call is asynchronous and that the callback contains the remote server&#39;s response.

HTTP GET Request in Node.js Express

I am learning nodejs at the moment on Windows. Several modules are installed globally with npm.cmd, and nodejs failed to find the installed modules. Take jade for example,

    npm install jade -g

Jade is installed in directory `&quot;C:\Program Files (x86)\nodejs\node_modules&quot;`, but the following code will fail with a `&quot;Cannot find module &#39;jade&#39;&quot;` error,

    var jade = require(&#39;jade&#39;);

However, the code will run successfully when jade is locally installed (without -g option in npm). I don&#39;t want to use locally-installed modules, it&#39;s a waste of disk space for me. How can I make the globally-installed modules work on Windows?

Nodejs cannot find installed module on Windows

I would like to retrieve some data from a Mongoose setting in my Node.js application. I noticed that no matter what I write as field selection, I always get the `_id` field. Is there a way not to fetch it?
This is how I do right now:

    Transaction.find({username : user.username}, [&#39;uniqueId&#39;, &#39;timeout&#39;, &#39;confirmation_link&#39;, &#39;item_name&#39;], function(err, txs){
    		console.log(&quot;user : &quot; + user.username + &quot; with txs: &quot; + txs);
    		callback(txs);
    });

And logs me the results which contain the `_id` field.

Mongoose retrieving data without _id field

We have an application that has two types of users. Depending on how the user logs in, we want them to have access to different parts of the application.

How do we implement a security model for preventing users from seeing things they do not have access to?

Do we make security part of each routes implementation? The problem being that we will have some duplicate logic across requests. We could move this into helper functions, but we&#39;d still need to remember to call it.

Do we make security part of a global app.all() route handler? The problem being that we have to inspect each route and do different logic based on a multitude of rules. At least all the code is in one place,  but then... all the code is in one place.

Node.js + Express.js User Permission Security Model

As far as I know, `initrd` acts as a block device, thus requiring a filesystem driver (such as `ext2`). The kernel must have at least one built-in module for detecting filesystem of `initrd`. In this article, [Introducing initramfs, a new model for initial RAM disks][1], it is written that:

&gt; But ramdisks actually waste even more memory due to caching. Linux is
&gt; designed to cache all files and directory entries read from or written
&gt; to block devices, so Linux copies data to and from the ramdisk into
&gt; the &quot;page cache&quot; (for file data), and the &quot;dentry cache&quot; (for
&gt; directory entries). The downside of the ramdisk pretending to be a
&gt; block device is it gets treated like a block device.

What&#39;s `page cache` and `dentry cache`? In the paragraph, does it mean the data got duplicated because `ramdisk` is treated as a block device, thus all the data is cached?

In constrast, `ramfs`:

&gt; A few years ago, Linus Torvalds had a neat idea: what if Linux&#39;s cache
&gt; could be mounted like a filesystem? Just keep the files in cache and
&gt; never get rid of them until they&#39;re deleted or the system reboots?
&gt; Linus wrote a tiny wrapper around the cache called &quot;ramfs&quot;, and other
&gt; kernel developers created an improved version called &quot;tmpfs&quot; (which
&gt; can write the data to swap space, and limit the size of a given mount
&gt; point so it fills up before consuming all available memory). Initramfs
&gt; is an instance of tmpfs.
&gt; 
&gt; These ram based filesystems automatically grow or shrink to fit the
&gt; size of the data they contain. Adding files to a ramfs (or extending
&gt; existing files) automatically allocates more memory, and deleting or
&gt; truncating files frees that memory. There&#39;s no duplication between
&gt; block device and cache, because there&#39;s no block device. The copy in
&gt; the cache is the only copy of the data. Best of all, this isn&#39;t new
&gt; code but a new application for the existing Linux caching code, which
&gt; means it adds almost no size, is very simple, and is based on
&gt; extremely well tested infrastructure.

In sum, `ramfs` is just file opened and loaded into memory, isn&#39;t it? 

Both `initrd` and `ramfs` are zipped at compile time, but the difference is, `initrd` is a block device unpacked to be mounted by the kernel at booting, while `ramfs` is unpacked via cpio into memory. Am I correct? Or is `ramfs` a very minimal file system?

Finally, up until this day, the `initrd` image is still presented in the latest kernel. However, is that `initrd` actually the `ramfs` used today and the name is just for historical purpose? 

  [1]: http://www.linuxfordevices.com/c/a/Linux-For-Devices-Articles/Introducing-initramfs-a-new-model-for-initial-RAM-disks/

The difference between initrd and initramfs?

I have a folder full of files and they don&#39;t have an extension. How can I check file types? I want to check the file type and change the filename accordingly. Let&#39;s assume a function `filetype(x)` returns a file type like `png`. I want to do this:

    files = os.listdir(&quot;.&quot;)
    for f in files:
        os.rename(f, f+filetype(f))

How do I do this?

How to check type of files without extensions?

When a file is created (`FileSystemWatcher_Created`) in one directory I copy it to another. But When I create a big (&gt;10MB) file it fails to copy the file, because it starts copying already, when the file is not yet finished creating...  
This causes **Cannot copy the file, because it&#39;s used by another process** to be raised. ;(  
Any help?


    class Program
    {
        static void Main(string[] args)
        {
            string path = @&quot;D:\levan\FolderListenerTest\ListenedFolder&quot;;
            FileSystemWatcher listener; 
            listener = new FileSystemWatcher(path);
            listener.Created += new FileSystemEventHandler(listener_Created);
            listener.EnableRaisingEvents = true;
    
            while (Console.ReadLine() != &quot;exit&quot;) ;
        }
    
        public static void listener_Created(object sender, FileSystemEventArgs e)
        {
            Console.WriteLine
                    (
                        &quot;File Created:\n&quot;
                       + &quot;ChangeType: &quot; + e.ChangeType
                       + &quot;\nName: &quot; + e.Name
                       + &quot;\nFullPath: &quot; + e.FullPath
                    );
            File.Copy(e.FullPath, @&quot;D:\levan\FolderListenerTest\CopiedFilesFolder\&quot; + e.Name);
            Console.Read();
        }
    }

Wait Until File Is Completely Written

I want to get the file names of all files that have a specific extension in a given folder (and recursively, its subfolders).  That is, the file name (and extension), not the full file path.  This is incredibly simple in languages like Python, but I&#39;m not familiar with the constructs for this in C++.   How can it be done?

How to get list of files with a specific extension in a given folder?

I have a file structure like this:

    root
    |_ fruits
    |___ apple
    |______images
    |________ apple001.jpg
    |________ apple002.jpg
    |_ animals
    |___ cat
    |______images
    |________ cat001.jpg
    |________ cat002.jpg


I would like to, using Javascript and Node.js, listen to this root directory and all sub directories and create a JSON which mirrors this directory structure, each node contains type, name, path, and children:

    data = [
      {
        type: &quot;folder&quot;,
        name: &quot;animals&quot;,
        path: &quot;/animals&quot;,
        children: [
          {
            type: &quot;folder&quot;,
            name: &quot;cat&quot;,
            path: &quot;/animals/cat&quot;,
            children: [
              {
                type: &quot;folder&quot;,
                name: &quot;images&quot;,
                path: &quot;/animals/cat/images&quot;,
                children: [
                  {
                    type: &quot;file&quot;,
                    name: &quot;cat001.jpg&quot;,
                    path: &quot;/animals/cat/images/cat001.jpg&quot;
                  }, {
                    type: &quot;file&quot;,
                    name: &quot;cat001.jpg&quot;,
                    path: &quot;/animals/cat/images/cat002.jpg&quot;
                  }
                ]
              }
            ]
          }
        ]
      }
    ];

Here&#39;s a coffeescript JSON:

    data = 
    [
      type: &quot;folder&quot;
      name: &quot;animals&quot;
      path: &quot;/animals&quot;
      children  :
        [
          type: &quot;folder&quot;
          name: &quot;cat&quot;
          path: &quot;/animals/cat&quot;
          children:
            [
              type: &quot;folder&quot;
              name: &quot;images&quot;
              path: &quot;/animals/cat/images&quot;
              children: 
                [
                  type: &quot;file&quot;
                  name: &quot;cat001.jpg&quot;
                  path: &quot;/animals/cat/images/cat001.jpg&quot;
                , 
                  type: &quot;file&quot;
                  name: &quot;cat001.jpg&quot;
                  path: &quot;/animals/cat/images/cat002.jpg&quot;
                ]
            ]
        ]
    ]


how to get this json data format in django views?(python)






Content Type	Original Author	Original Content on Stackoverflow
Question	mesh	View Question on Stackoverflow
Solution 1 - node.js	maerics	View Answer on Stackoverflow
Solution 2 - node.js	user2248133	View Answer on Stackoverflow

nodejs - How to read and output jpg image?

node.js Problem Overview

node.js Solutions

Solution 1 - node.js

Solution 2 - node.js

Scala - mutable (var) method parameter reference

How to find if a Scala String is parseable as a Double or not?

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