You can use the `path` module to join the path of the directory in which `helper1.js` lives to the relative path of `foobar.json`. This will give you the absolute path to `foobar.json`.

    var fs = require(&#39;fs&#39;);
    var path = require(&#39;path&#39;);
    
    var jsonPath = path.join(__dirname, &#39;..&#39;, &#39;config&#39;, &#39;dev&#39;, &#39;foobar.json&#39;);
    var jsonString = fs.readFileSync(jsonPath, &#39;utf8&#39;);

This should work on Linux, OSX, and Windows assuming a UTF8 encoding.

Simple! The folder named `..` is the parent folder, so you can make the path to the file you need as such

    var foobar = require(&#39;../config/dev/foobar.json&#39;);

If you needed to go up two levels, you would write `../../` etc

Some more details about this in [this SO answer][1] and it&#39;s comments 


  [1]: https://stackoverflow.com/a/7165572/1311745

I&#39;m trying to test if a Swift string starts or ends with a certain value. These methods do not exist:

    var str = &quot;Hello, playground&quot;
    str.startsWith(&quot;Hello&quot;) // error
    str.endsWith(&quot;ground&quot;) // error

I would also like to get the prefix and suffix strings. I could find a substring, as is answered [here][1] and [here][2], but ranges are such a pain in Swift.

Is there an easier way to do it?

*(I stumbled across the answer when I was reading [the documentation][3], and since an SO answer didn&#39;t come up for my search terms, I am adding my Q&amp;A here.)*


  [1]: https://stackoverflow.com/questions/24044851/how-do-you-use-string-substringwithrange-or-how-do-ranges-work-in-swift
  [2]: https://stackoverflow.com/questions/28182441/swift-how-to-get-substring-from-start-to-last-index-of-character
  [3]: https://developer.apple.com/library/ios/documentation/Swift/Conceptual/Swift_Programming_Language/StringsAndCharacters.html

How to check what a String starts with (prefix) or ends with (suffix) in Swift

I&#39;ve recently tried to install package through Composer, but I have got an error ` the requested PHP extension mbstring is missing from your system.`
I removed semicolon from `php.ini`, but it still doesn&#39;t work. What should I do?

Composer - the requested PHP extension mbstring is missing from your system

It seemed like a straight forward problem. But I amn&#39;t able to crack this.
Within helper1.js I would like to access foobar.json (from `config/dev/`)

    root
      -config
       --dev
        ---foobar.json
      -helpers
       --helper1.js

I couldn&#39;t get this to work https://stackoverflow.com/questions/7083045/fs-how-do-i-locate-a-parent-folder 

Any help here would be great.

NodeJS accessing file with relative path

It seemed like a straight forward problem. But I amn't able to crack this.
Within helper1.js I would like to access foobar.json (from <code>config/dev/</code>)
<pre><code class="hljs language-lua">root
 -config
 --dev
 ---foobar.json
 -helpers
 --helper1.js
</code></pre>
I couldn't get this to work <a href="https://stackoverflow.com/questions/7083045/fs-how-do-i-locate-a-parent-folder" target="_blank" rel="noopener noreferrer">https://stackoverflow.com/questions/7083045/fs-how-do-i-locate-a-parent-folder</a>
Any help here would be great.

I installed Node JS several months ago and played around a bit. Today, I wanted to start learning more about node and before coding, I decided I wanted to make sure I had the latest version.

I checked the version and it was something like v0.10.3x. I looked on the NodeJS website and it shows the latest version as v4.1.0. So I thought Woahhh! I better upgrade and I couldn&#39;t believe it moved that fast to a 4.x version in only a few months.

I spent quite some time trying to figure out how to completely uninstall node and npm because I couldn&#39;t seem to upgrade it.

Finally I got it all ripped out, then installed in on CentOS 7 using yum. I know I won&#39;t get the latest version through yum but, I figured it would be close enough.

After install, I am at v0.10.40.

I have a feeling I just don&#39;t understand something about NodeJS version numbers.

NodeJS version number confusion

I have an empty new project, when i run npm init i got a list of questions to answer, for example:
    
    name: (karma)
    version: (1.0.0)
    description:my project description
    entry point: (index.js)


I am really confused about the one that says &quot;entry point&quot;, Should this be my index.html file or my app.js or is it something else?

What is &quot;entry point&quot; in npm init

Below is my code
    
    var mongoose = require(&#39;mongoose&#39;);
    mongoose.connect(&#39;mongodb://localhost/test&#39;);

    var Cat = mongoose.model(&#39;Cat&#39;, {
        name: String,
        age: {type: Number, default: 20},
        create: {type: Date, default: Date.now} 
    });

    Cat.findOneAndUpdate({age: 17}, {$set:{name:&quot;Naomi&quot;}},function(err, doc){
        if(err){
            console.log(&quot;Something wrong when updating data!&quot;);
        }

        console.log(doc);
    });

I already have some record in my mongo database and I would like to run this code to update name for which age is 17 and then print result out in the end of code.

However, why I still get same result from console(not the modified name) but when I go to mongo db command line and type &quot;`db.cats.find();`&quot;. The result came with modified name.

Then I go back to run this code again and the result is modified.

My question is:  If the data was modified, then why I still got original data at first time when console.log it.

 

Mongoose: findOneAndUpdate doesn&#39;t return updated document

So I made the mistake of trying to get rid of all sudo dependencies. I downloaded npm as a package from the site and did a manual/global install. But it seemed as if i was always having to run with sudo...so I tried to uninstall and run with homebrew.

Now I can&#39;t get node or npm to even run...I guess I have to link with brew link them but i&#39;m getting this error:

    Could not symlink share/doc/node/gdbinit
    Target /usr/local/share/doc/node/gdbinit
    already exists. You may want to remove it:
      rm &#39;/usr/local/share/doc/node/gdbinit&#39;


I&#39;ve tried removing that:
And i&#39;ve gotten permission denied.

I have tried running brew prune.
I have tried to uninstall then reinstall using these steps:

    $ brew uninstall npm
    $ brew uninstall node
    $ npm uninstall npm -g
    $ sudo rm -rf /usr/local/lib/node_module

https://stackoverflow.com/questions/12607155/error-the-brew-link-step-did-not-complete-successfully

I am running Yosemite 10.10.5. I have git version 2.6.0 installed. My homebrew is updated. A brew doctor gives me this warning:

    Warning: You have unlinked kegs in your Cellar
    Leaving kegs unlinked can lead to build-trouble and cause brews that depend on
    those kegs to fail to run properly once built. Run `brew link` on these:
        node

 Not sure where to go from here. I&#39;m trying to lose my reliance on CodeKit and get gulp up and running.

Homebrew npm install: could not symlink

I need to webpack all the js file in the script folder.I tried this 

    module.exports = {
      module: {
        loaders: [
          {
            test: /\.js$/,
            exclude: /node_modules/,
            loaders: [&quot;babel-loader&quot;],
          }
        ],
      },
      entry: &quot;./src/scripts/*.js&quot;,
      output: {
        path: &#39;./src/build&#39;,
        filename: &#39;[name].js&#39;
      }
    };
 I am getting  error like this,

    ERROR in Entry module not found: Error: Cannot resolve &#39;file&#39; or &#39;directory&#39; ./s
    rc/scripts/* in E:\Web project\ReactJS\react-tutorial
    resolve file
      E:\Web project\ReactJS\react-tutorial\src\scripts\* doesn&#39;t exist
      E:\Web project\ReactJS\react-tutorial\src\scripts\*.webpack.js doesn&#39;t exist
      E:\Web project\ReactJS\react-tutorial\src\scripts\*.web.js doesn&#39;t exist
      E:\Web project\ReactJS\react-tutorial\src\scripts\*.js doesn&#39;t exist
      E:\Web project\ReactJS\react-tutorial\src\scripts\*.json doesn&#39;t exist
    resolve directory
      E:\Web project\ReactJS\react-tutorial\src\scripts\* doesn&#39;t exist (directory d
    efault file)
      E:\Web project\ReactJS\react-tutorial\src\scripts\*\package.json doesn&#39;t exist
     (directory description file)
It is not searching for all the js file instead it is searching for *.js like that.Help me out what I missed 

How to add wildcard mapping in entry of webpack

Basically I have a mongodb collection called &#39;people&#39;
whose schema is as follows: 

    people: {
             name: String, 
             friends: [{firstName: String, lastName: String}]
            }

Now, I have a very basic express application that connects to the database and successfully creates &#39;people&#39; with an empty friends array.

In a secondary place in the application, a form is in place to add friends. The form takes in firstName and lastName and then POSTs with the name field also for reference to the proper people object. 

What I&#39;m having a hard time doing is creating a new friend object and then &quot;pushing&quot; it into the friends array.

I know that when I do this via the mongo console I use the update function with `$push` as my second argument after the lookup criteria, but I can&#39;t seem to find the appropriate way to get mongoose to do this.

    db.people.update({name: &quot;John&quot;}, {$push: {friends: {firstName: &quot;Harry&quot;, lastName: &quot;Potter&quot;}}});

Push items into mongo array via mongoose

I have a lot of ES6 promise based code running inside my express app. If there is an error that is never caught I&#39;m using the following code to deal with it:

    process.on(&#39;unhandledRejection&#39;, function(reason, p) {
      console.log(&quot;Unhandled Rejection:&quot;, reason.stack);
      process.exit(1);
    });

This works fine for debugging purposes. 

In production however I would like to trigger the 500 error handler, to show the user the standard &quot;Something went wrong&quot; page. I have this catch all error handler that currently works for other exceptions:

    
    app.use(function(error, req, res, next) {
      res.status(500);
      res.render(&#39;500&#39;);
    });

Putting the unhandledRejection inside a middleware does not work as it&#39;s async and offen results in a `Error: Can&#39;t render headers after they are sent to the client.`

How would I go about rendering the 500 page on an `unhandledRejection`?


Unhandled rejections in Express applications

There are some similar questions asked but my question is that if I want to  propagate intermediate results that I get along the different routing middleware, what is the best way to do that?  
 
    app.use(f1); app.use(f2); app.use(f3);

    function f1(req,res,next) {
      //some database queries are executed and I get results, say x1
      res.locals.dbResults = {...};
      next();
    }

    function f2(req,res,next) {
      // more processing based upon req.locals.dbResults 
      res.locals.moreResults = {....};
      next();
    }
    // ...

I think that I can get the same propagation of data through the different middleware by using **req**.locals. Also, it appears that the request and response objects both have the locals properties initialized to an empty object at the start of the request.

Also, one can set res.mydata or req.mydata properties too?

In theory, app.locals can also be used for passing this data along through the different middleware as it will persist across middlewares but that would be contrary to the conventional use of app.locals. It is used more for application specific data. It will also be necessary to clear that data at the end of the request-response cycle so the same variables can be used for the next request.

**What is the optimal and standard way to propagate intermediate results through middleware?**

req.locals vs. res.locals vs. res.data vs. req.data vs. app.locals in Express middleware

I&#39;m very new for this stuff, and trying to make some express app

    var express = require(&#39;express&#39;);
    var app = express();

    app.listen(3000, function(err) {
        if(err){
           console.log(err);
           } else {
           console.log(&quot;listen:3000&quot;);
        }
    });

    //something useful
    app.get(&#39;*&#39;, function(req, res) {
      res.status(200).send(&#39;ok&#39;)
    });

When I start the server with the command: 

    node server.js 

everything goes fine.

I see on the console
    
    listen:3000

and when I try

    curl http://localhost:3000

I see &#39;ok&#39;. 

When I try 

    telnet localhost

I see

    Trying 127.0.0.1...
    Connected to localhost.
    Escape character is &#39;^]&#39; 

but when I try 

    netstat -na | grep :3000

I see

    tcp  0  0 0.0.0.0:3000   0.0.0.0:*  LISTEN


The question is: why does it listen all interfaces instead of only localhost?

The OS is linux mint 17 without any whistles.


express app server . listen all interfaces instead of localhost only

# My Issue
I&#39;ve coded a very simple CRUD API and I&#39;ve started recently coding also some tests using `chai` and `chai-http` but I&#39;m having an issue when running my tests with `$ mocha`.

When I run the tests I get the following error on the shell:

&gt; TypeError: app.address is not a function

## My Code

Here is a sample of one of my tests (**/tests/server-test.js**):

    var chai = require(&#39;chai&#39;);
    var mongoose = require(&#39;mongoose&#39;);
    var chaiHttp = require(&#39;chai-http&#39;);
    var server = require(&#39;../server/app&#39;); // my express app
    var should = chai.should();
    var testUtils = require(&#39;./test-utils&#39;);
    
    chai.use(chaiHttp);
    
    describe(&#39;API Tests&#39;, function() {
      before(function() {
        mongoose.createConnection(&#39;mongodb://localhost/bot-test&#39;, myOptionsObj);
      });
    
      beforeEach(function(done) {
        // I do stuff like populating db
      });
    
      afterEach(function(done) {
        // I do stuff like deleting populated db
      });
    
      after(function() {
        mongoose.connection.close();
      });
    
      describe(&#39;Boxes&#39;, function() {
    
        it.only(&#39;should list ALL boxes on /boxes GET&#39;, function(done) {
          chai.request(server)
            .get(&#39;/api/boxes&#39;)
            .end(function(err, res){
              res.should.have.status(200);
              done();
            });
        });
    
        // the rest of the tests would continue here...
    
      });
    
    });

And my `express` app files (**/server/app.js**):

    var mongoose = require(&#39;mongoose&#39;);
    var express = require(&#39;express&#39;);
    var api = require(&#39;./routes/api.js&#39;);
    var app = express();
    
    mongoose.connect(&#39;mongodb://localhost/db-dev&#39;, myOptionsObj);
    
    // application configuration
    require(&#39;./config/express&#39;)(app);
    
    // routing set up
    app.use(&#39;/api&#39;, api);
    
    var server = app.listen(3000, function () {
      var host = server.address().address;
      var port = server.address().port;
    
      console.log(&#39;App listening at http://%s:%s&#39;, host, port);
    });

and (**/server/routes/api.js**):

    var express = require(&#39;express&#39;);
    var boxController = require(&#39;../modules/box/controller&#39;);
    var thingController = require(&#39;../modules/thing/controller&#39;);
    var router = express.Router();
    
    // API routing
    router.get(&#39;/boxes&#39;, boxController.getAll);
    // etc.
    
    module.exports = router;

### Extra notes

I&#39;ve tried logging out the `server` variable in the **/tests/server-test.js** file before running the tests:

    ...
    var server = require(&#39;../server/app&#39;); // my express app
    ...
    
    console.log(&#39;server: &#39;, server);
    ...

and I the result of that is an empty object: `server: {}`.

Mocha API Testing: getting &#39;TypeError: app.address is not a function&#39;

I want to use Node.js to create a simple logging system which prints a line before the past line into a .txt file. However, I don&#39;t know how the file system functionality from Node.js works.

Can someone explain it?



Write a line into a .txt file with Node.js

I have a file(`data.file` an image), I would like to save this image. Now an image with the same name *could* exist before it. I would like to overwrite if so or create it if it does not exist since before. I read that the flag &quot;w&quot; should do this.

Code:

```js
fs.writeFile(&#39;/avatar/myFile.png&#39;, data.file, {
  flag: &quot;w&quot;
}, function(err) {
  if (err) {
    return console.log(err);
  }
  console.log(&quot;The file was saved!&quot;);
});
```

Error:

&gt; ```yaml
&gt; [Error: ENOENT: no such file or directory, open &#39;/avatar/myFile.png&#39;]
&gt; errno: -2,
&gt;   code: &#39;ENOENT&#39;,
&gt;     syscall: &#39;open&#39;,
&gt;       path: &#39;/avatar/myFile.png&#39;
&gt; ```


writeFile no such file or directory

I am trying to write JSON file using node from loop data, e.g.:

&lt;!-- language: lang-js --&gt;

    let jsonFile = require(&#39;jsonfile&#39;);
    
    for (i = 0; i &lt; 11; i++) {
        jsonFile.writeFile(&#39;loop.json&#39;, &quot;id :&quot; + i + &quot; square :&quot; + i * i);
    }

outPut in loop.json is:

    id :1 square : 1

but I want output file like this (below) and also if I run that code again it should add that new output as elements in same existing JSON file:

&lt;!-- language: lang-json --&gt;

    {
       &quot;table&quot;:[
          {
             &quot;Id &quot;:1,
             &quot;square &quot;:1
          },
          {
             &quot;Id &quot;:2,
             &quot;square &quot;:3
          },
          {
             &quot;Id &quot;:3,
             &quot;square &quot;:9
          },
          {
             &quot;Id &quot;:4,
             &quot;square &quot;:16
          },
          {
             &quot;Id &quot;:5,
             &quot;square &quot;:25
          },
          {
             &quot;Id &quot;:6,
             &quot;square &quot;:36
          },
          {
             &quot;Id &quot;:7,
             &quot;square &quot;:49
          },
          {
             &quot;Id &quot;:8,
             &quot;square &quot;:64
          },
          {
             &quot;Id &quot;:9,
             &quot;square &quot;:81
          },
          {
             &quot;Id &quot;:10,
             &quot;square &quot;:100
          }
       ]
    }

I want to use same file that I created 1st time but whenever I run that code new elements should add in that same file

&lt;!-- language: lang-js --&gt;

    const fs = require(&#39;fs&#39;);
    
    let obj = {
        table: []
    };
    
    fs.exists(&#39;myjsonfile.json&#39;, function(exists) {
    
        if (exists) {
    
            console.log(&quot;yes file exists&quot;);
    
            fs.readFile(&#39;myjsonfile.json&#39;, function readFileCallback(err, data) {
    
                if (err) {
                    console.log(err);
                } else {
                    obj = JSON.parse(data);
    
                    for (i = 0; i &lt; 5; i++) {
                        obj.table.push({
                            id: i,
                            square: i * i
                        });
                    }
    
                    let json = JSON.stringify(obj);
                    fs.writeFile(&#39;myjsonfile.json&#39;, json);
                }
            });
        } else {

            console.log(&quot;file not exists&quot;);

            for (i = 0; i &lt; 5; i++) {
                obj.table.push({
                    id: i,
                    square: i * i
                });
            }

            let json = JSON.stringify(obj);
            fs.writeFile(&#39;myjsonfile.json&#39;, json);
        }
    });

  [1]: http://stackoverflow.com/users/5653484/kailniris
  [2]: http://stackoverflow.com/users/2630100/zamboney

Write / add data in JSON file using Node.js

I would like to use async/await with some filesystem operations. Normally async/await works fine because I use `babel-plugin-syntax-async-functions`.

But with this code I run into the if case where `names` is undefined:


    import fs from &#39;fs&#39;;
    
    async function myF() {
      let names;
      try {
        names = await fs.readdir(&#39;path/to/dir&#39;);
      } catch (e) {
        console.log(&#39;e&#39;, e);
      }
      if (names === undefined) {
        console.log(&#39;undefined&#39;);
      } else {
        console.log(&#39;First Name&#39;, names[0]);
      }
    }
    
    myF();

When I rebuild the code into the callback hell version everything is OK and I get the filenames.
Thanks for your hints.

Using filesystem in node.js with async / await

I have a little problem with my function. I would like to get all files in many directories. Currently, I can retrieve the files in the file passed in parameters. I would like to retrieve the html files of each folder in the folder passed as a parameter. I will explain if I put in parameter &quot;test&quot; I retrieve the files in &quot;test&quot; but I would like to retrieve &quot;test / 1 / *. Html&quot;, &quot;test / 2 / *. /*.html &quot;:   

    var srcpath2 = path.join(&#39;.&#39;, &#39;diapo&#39;, result);
    function getDirectories(srcpath2) {
                    return fs.readdirSync(srcpath2).filter(function (file) {
                        return fs.statSync(path.join(srcpath2, file)).isDirectory();
                    });
                }

The result :
[1,2,3]

thanks !

Content Type	Original Author	Original Content on Stackoverflow
Question	lonelymo	View Question on Stackoverflow
Solution 1 - node.js	AerandiR	View Answer on Stackoverflow
Solution 2 - node.js	AdityaParab	View Answer on Stackoverflow

NodeJS accessing file with relative path

node.js Problem Overview

node.js Solutions

Solution 1 - node.js

Solution 2 - node.js

Composer - the requested PHP extension mbstring is missing from your system

How to check what a String starts with (prefix) or ends with (suffix) in Swift

Attributions