See [the documentation](https://docs.npmjs.com/files/package.json#engines) which includes examples.

Provide a space separated list of engines with greater/less than symbols.

    { 
      &quot;engines&quot; : { 
        &quot;node&quot; : &quot;&gt;=8.0.0 &lt;11.0.0&quot; 
      }
    }


You just need the double pipe `||` instead of a single.

    &quot;engines&quot;: {
      &quot;node&quot;: &quot;^8 || ^10&quot;
    }

Would match either v8.x.x or v10.x.x but _not_ v9.

You can read more about it here https://docs.npmjs.com/files/package.json#dependencies

**Introduction**

I have this favorite algorithm that I&#39;ve made quite some time ago which I&#39;m always writing and re-writing in new programming languages, platforms etc. as some sort of benchmark. Although my main programming language is C# I&#39;ve just quite literally copy-pasted the code and changed the syntax slightly, built it in Java and found it to run 1000x faster.

**The Code**

There is quite a bit of code but I&#39;m only going to present this snippet which seems to be the main issue:

    for (int i = 0; i &lt;= s1.Length; i++) 
    {
        for (int j = i + 1; j &lt;= s1.Length - i; j++)
        {
            string _s1 = s1.Substring(i, j);
            if (tree.hasLeaf(_s1))
             ...

**The Data**

It is important to point out that the string s1 in this particular test is of length 1 milion characters (1MB). 

**Measurements**

I have profiled my code execution in Visual Studio because I thought the way I construct my tree or the way I traverse it isn&#39;t optimal. After examining the results it appears that the line `string _s1 = s1.Substring(i, j);` is accommodating for over 90% of the execution time!

**Additional Observations**

Another difference that I&#39;ve noticed is that although my code is single threaded Java manages to execute it using all 8 cores (100% CPU utilization) while even with Parallel.For() and multi threading techniques my C# code manages to utilize 35-40% at most. Since the algorithm scales linearly with the number of cores (and frequency) I have compensated for this and still the snippet in Java executes order of magnitude 100-1000x faster.

**Reasoning**

I presume that the reason why this is happening has to do with the fact that strings in C# are immutable so String.Substring() has to create a copy and since it&#39;s within a nested for loop with many iterations I presume a lot of copying and garbage collecting is going on, however, I don&#39;t know how Substring is implemented in Java.

**Question**

What are my options at this point? There is no way around the number and length of substrings (this is already optimized maximally). Is there a method that I don&#39;t know of (or data structure perhaps) that could solve this issue for me?

**Requested Minimal Implementation (from comments)**

I have left out the implementation of the suffix tree which is O(n) in construction and O(log(n)) in traversal

    public static double compute(string s1, string s2)
    {
        double score = 0.00;
        suffixTree stree = new suffixTree(s2);
        for (int i = 0; i &lt;= s1.Length; i++) 
        {
            int longest = 0;
            for (int j = i + 1; j &lt;= s1.Length - i; j++)
            {
                string _s1 = s1.Substring(i, j);
                if (stree.has(_s1))
                {
                    score += j - i;
                    longest = j - i;
                }
                else break;
             };

            i += longest;
        };
        return score;
    }

**Screenshot snippet of the profiler**

Note this was tested with string s1 the size of 300.000 characters. For some reason 1 milion characters just never finishes in C# while in Java it takes only 0.75 seconds.. The memory consumed and number of garbage collections don&#39;t seem to indicate a memory issue. The peak was about 400 MB but considering the huge suffix tree this appears to be normal. No weird garbage collecting patterns spotted either.

[![CPU profiler][1]][1]


[![Memory profiler][2]][2]


  [1]: https://i.stack.imgur.com/6rEGQ.png
  [2]: https://i.stack.imgur.com/58bHc.png

String.Substring() seems to bottleneck this code

Hello I have a tab bar in Flutter and I want to disable swiping between tabs


     
          // Set the bottom navigation bar
          bottomNavigationBar: new Material(
    
            // set the color of the bottom navigation bar
            color: const Color(0xFFF7F7F7),
            // set the tab bar as the child of bottom navigation bar
            child: new TabBar(
              tabs: &lt;Tab&gt;[
                new Tab(
                  // set icon to the tab
                  icon: new Icon(Icons.home,color: Colors.black),
                ),
                new Tab(
                  icon: new Icon(Icons.favorite,color: Colors.black),
                ),
                new Tab(
                  icon: new Icon(Icons.search,color: Colors.black),
                ),
                new Tab(
                  icon: new Icon(Icons.settings,color: Colors.black),
                ),
              ],
              // setup the controller
              controller: controller,
    
    
            ),
          ),
        );
      }
    }




I am moving tabs on clicking each tab bar button and I want to disable swiping thank you


disable swiping tabs in TabBar flutter

I tried to specify the node engine in a package.json to accept both `8` and `10` version.

I tried to type this:

    &quot;engines&quot;: {
      &quot;node&quot;: &quot;8.x|10.x&quot;
    },

But running `yarn` results in:

&gt; The engine &quot;node&quot; is incompatible with this module. Expected version &quot;8.x|10.x&quot;

If I replace with:


    &quot;engines&quot;: {
      &quot;node&quot;: &quot;10.x&quot;
    },

... it works (i.e no error).

Is there a way to accept two versions of node engine in a `package.json`?


Node engine 8.x or 10.x in package.json

I tried to specify the node engine in a package.json to accept both <code>8</code> and <code>10</code> version.
I tried to type this:
<pre><code class="hljs language-json">"engines": {
 "node": "8.x|10.x"
},
</code></pre>
But running <code>yarn</code> results in:
> The engine "node" is incompatible with this module. Expected version "8.x|10.x"
If I replace with:
<pre><code class="hljs language-json">"engines": {
 "node": "10.x"
},
</code></pre>
... it works (i.e no error).
Is there a way to accept two versions of node engine in a <code>package.json</code>?

I&#39;m attempting to find an object in an array using `Array.prototype.includes`. Is this possible? I realize there is a difference between shallow and deep comparison. Is that the reason the below code returns false? I could not find a relevant answer for `Array.includes()`.

[![dev tools console][1]][1]

  [1]: https://i.stack.imgur.com/7pkYo.png

Array.includes() to find object in array

How can I make a **Material UI** react `Button` component act as a `Link` component from **react-router-dom** without losing it&#39;s original style? Like changing the route on click.

    import Button from &#39;@material-ui/core/Button&#39;;
    
    &lt;Button variant=&quot;contained&quot; color=&quot;primary&quot;&gt;
        About Page
    &lt;/Button&gt;

To something like this, but maintaining the original `Button` style:

    import Button from &#39;@material-ui/core/Button&#39;;
    import { Link } from &#39;react-router-dom&#39;;
        
    &lt;Button variant=&quot;contained&quot; color=&quot;primary&quot;&gt;
        &lt;Link to=&quot;/about&quot;&gt;
            About Page
        &lt;/Link&gt;
    &lt;/Button&gt;

How to make a Material UI react Button act as a react-router-dom Link?

I&#39;m having trouble figuring out how to have multiple pages in a Vue CLI project. Right now I have my home page with a few components and I want to create another page but I do not know how to do that. Am I supposed to create multiple html files where the index.html by default is? In a simple file structure with css js img folder and html files as pages I know that creating another html file means making another page. But I don&#39;t understand how this works with Vue CLI project.

I saw stuff like vue-router and &quot;pages&quot; in Vue documentation but I do not understand them very well. What are my alternatives? Is there a guide that explains that in detail, because I wasn&#39;t able to find any, let alone detailed. Would be very happy if you could help! Thank you!

multiple pages in Vue.js CLI

&gt; npm start

starts the react server on the default browser, which is Firefox for me. I like Firefox for browsing but prefer Chrome in web development for its developer tools. Is there a way to force &quot;npm start&quot; to start the server with Chrome, without changing my default browser to chrome? I am using Bash on Windows.

**Edit:** I used &quot;create-react-app&quot; to create my server and this adds a [script to &quot;packages.json&quot; file for &quot;npm start&quot;](https://i.imgur.com/j8DLTWU.png). The script starts the localhost server with the default browser. How do I modify the script added by &quot;create-react-app&quot; such that it starts with a different browser?

create-react-app: How do I &quot;npm start&quot; with a specific browser?

I have a the below code, on which i am unable to break the loop on certain conditions.

     isVoteTally(): boolean {
   

     let count = false;
        this.tab.committee.ratings.forEach(element =&gt; {
    
          const _fo = this.isEmptyOrNull(element.ratings.finalOutcome.finaloutlook);
          const _foreign = this.isEmptyOrNull(element.ratings.finalOutcome.foreign);
          const _local = this.isEmptyOrNull(element.ratings.finalOutcome.local);
          const _tally = element.ratings.finalOutcome.voteTally.maj + element.ratings.finalOutcome.voteTally.dis;
    
          if (_fo == false &amp;&amp; _foreign == false &amp;&amp; _local == false) {
            if (_tally &gt; 0) {
              **return count = false;**
            }
          } else {
            if (_tally &lt; 0) {
              **return count = false;**
            }
          }
        });
        return count;
      }

On the star-marked area, i want to *break* the code and return the boolean value, but i am unable to do it right now. Can anybody help me.

Thanks in advance.




How to break ForEach Loop in TypeScript

I&#39;m trying to install IPFS from [here](https://github.com/ipfs/js-ipfs#install)``` npm install ipfs --save ```  and it is giving me the error as  

&gt; npm ERR! tar.unpack error reading /media/FLASH/Tech/IPFS/ipfs
&gt;
&gt; npm ERR! addLocal Could not install /media/FLASH/Tech/IPFS/ipfs
&gt;
&gt; npm ERR! Linux 4.15.0-29-generic
&gt;
&gt; npm ERR! argv &quot;/usr/local/bin/node&quot; &quot;/usr/local/bin/npm&quot; &quot;install&quot; &quot;ipfs&quot;
&quot;--save&quot;
&gt;
&gt; npm ERR! node v6.9.2
&gt;
&gt; npm ERR! npm  v3.10.9
&gt; 
&gt; npm ERR! 0-byte tarball
&gt;
&gt; npm ERR! Please run npm cache clean

I tried doing ``` npm cache clean``` but still it is giving me the same error while doing ``` npm install ipfs --save ``` 

I don&#39;t know why I&#39;m getting this error. and how to avoid this error.  

Please run `npm cache clean`

I&#39;m using tsc build tasks. Unfortunately I&#39;m always getting the same errors from the node modules folder

    Executing task: .\node_modules\.bin\tsc.cmd --watch -p .\tsconfig.json &lt;
    node_modules/@types/node/index.d.ts(6208,55): error TS2304: Cannot find name &#39;Map&#39;.
    node_modules/@types/node/index.d.ts(6215,55): error TS2304: Cannot find name &#39;Set&#39;.
    node_modules/@types/node/index.d.ts(6219,64): error TS2304: Cannot find name &#39;Symbol&#39;.
    node_modules/@types/node/index.d.ts(6225,59): error TS2304: Cannot find name &#39;WeakMap&#39;.
    node_modules/@types/node/index.d.ts(6226,59): error TS2304: Cannot find name &#39;WeakSet&#39;.
    10:13:18 - Compilation complete. Watching for file changes.

I already added the directory to the ignore at `tsconfig.json`
```json

    {
      &quot;compilerOptions&quot;: {
        &quot;target&quot;: &quot;es5&quot;,
        &quot;module&quot;: &quot;commonjs&quot;,
        &quot;sourceMap&quot;: true,
        &quot;strict&quot;: false,
        &quot;noImplicitAny&quot;: false,
        &quot;strictPropertyInitialization&quot;: false,
        &quot;esModuleInterop&quot;: true,
      },
      &quot;include&quot;: [
        &quot;src/*&quot;
      ],
      &quot;exclude&quot;: [
        &quot;node_modules&quot;,
        &quot;./node_modules&quot;,
        &quot;./node_modules/*&quot;,
        &quot;./node_modules/@types/node/index.d.ts&quot;,
      ]
    }
```
What I&#39;m doing wrong? What should I do in order to ignore those errors?

I&#39;m using VsCode and tsc Version 2.9.2

How to force tsc to ignore node_modules folder?

Tried to run this command on ubuntu 18.04

    npm install -g pngquant-bin

but I got this error, 

    [..................] | fetchMetadata: sill resolveWithNewModule npm-conf@1.1.3 checking installable status
    npm WARN deprecated gulp-util@3.0.8: gulp-util is deprecated - replace it, following the guidelines at https://medium.com/gulpjs/gulp-util-ca3b1f9f9ac5
    /root/.nvm/versions/node/v10.8.0/bin/pngquant -&gt; /root/.nvm/versions/node/v10.8.0/lib/node_modules/pngquant-bin/cli.js
    
    &gt; pngquant-bin@5.0.0 postinstall /root/.nvm/versions/node/v10.8.0/lib/node_modules/pngquant-bin
    &gt; node lib/install.js
    
    sh: 1: node: Permission denied
    npm ERR! file sh
    npm ERR! code ELIFECYCLE
    npm ERR! errno ENOENT
    npm ERR! syscall spawn
    npm ERR! pngquant-bin@5.0.0 postinstall: `node lib/install.js`
    npm ERR! spawn ENOENT
    npm ERR!
    npm ERR! Failed at the pngquant-bin@5.0.0 postinstall script.
    npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
    
    npm ERR! A complete log of this run can be found in:
    npm ERR!     /root/.npm/_logs/2018-08-12T18_08_02_197Z-debug.log

Do you do you know how to deal with this?
I tried every solution found in this [articles][1] yet not succeeded.

  [1]: https://github.com/imagemin/pngquant-bin/issues/78

sh: 1: node: Permission denied

I&#39;ve got a `PlayersModule` and an `ItemsModule`.

I want to use the `ItemsService` in the `PlayersService`.

When I add it by injection:

    import { Injectable } from &#39;@nestjs/common&#39;;
    import { InjectModel } from &#39;nestjs-typegoose&#39;;
    import { ModelType, Ref } from &#39;typegoose&#39;;
    import { Player } from &#39;./player.model&#39;;
    import { Item } from &#39;../items/item.model&#39;;
    import { ItemsService } from &#39;../items/items.service&#39;;
    
    @Injectable()
    export class PlayersService {
        constructor(
            @InjectModel(Player) private readonly playerModel: ModelType&lt;Player&gt;,
            private readonly itemsService: ItemsService){}

I get this nest error :

&gt; [Nest] 11592   - 2018-8-13 11:42:17   [ExceptionHandler] Nest can&#39;t
&gt; resolve dependencies of the PlayersService (+, ?). Please make sure
&gt; that the argument at index [1] is available in the current context.

Both modules are imported in the `app.module.ts`. Both services are working alone in their module.

Inject nestjs service from another module

need pinned resolution feature of yarn, but also want to audit with `npm audit`? Is there a yarn alternative to `npm audit`? Or, alternately, will pinning resolutions of dependencies of dependencies work in `npm`?

is there a yarn alternative for npm audit?

I am trying to build a react app, but when I execute the command `npm -i` it gives me the following error:

    Error: Failed to replace env in config: ${NPM_TOKEN}
        at /usr/local/lib/node_modules/npm/lib/config/core.js:415:13
        at String.replace (&lt;anonymous&gt;)
        at envReplace (/usr/local/lib/node_modules/npm/lib/config/core.js:411:12)
        at parseField (/usr/local/lib/node_modules/npm/lib/config/core.js:389:7)
        at /usr/local/lib/node_modules/npm/lib/config/core.js:330:24
        at Array.forEach (&lt;anonymous&gt;)
        at Conf.add (/usr/local/lib/node_modules/npm/lib/config/core.js:328:23)
        at ConfigChain.addString (/usr/local/lib/node_modules/npm/node_modules/config-chain/index.js:244:8)
        at Conf.&lt;anonymous&gt; (/usr/local/lib/node_modules/npm/lib/config/core.js:316:10)
        at /usr/local/lib/node_modules/npm/node_modules/graceful-fs/graceful-fs.js:78:16
    /usr/local/lib/node_modules/npm/lib/npm.js:61
          throw new Error(&#39;npm.load() required&#39;)
          ^
    
    Error: npm.load() required
        at Object.get (/usr/local/lib/node_modules/npm/lib/npm.js:61:13)
        at process.errorHandler (/usr/local/lib/node_modules/npm/lib/utils/error-handler.js:205:18)
        at process.emit (events.js:182:13)
        at process._fatalException (internal/bootstrap/node.js:448:27)

I am using MacOS High Sierra. I tried to set the NPM_TOKEN as an environment variable with following command:

    set -x NPM_TOKEN = xyz
but it doesn&#39;t work.
What is the problem?

NPM - Failed to replace env in config: ${NPM_TOKEN}

Is there an `npm` equivalent of the [yarn resolutions](https://yarnpkg.com/lang/en/docs/selective-version-resolutions/) functionality? There is no mention of it in the npm package.json [docs](https://docs.npmjs.com/files/package.json).

For example, I want to install `lerna@3.3.2` and one of its dependencies (@lerna/publish) at 3.3.2 as well. Currently doing that with `yarn` like so, but would prefer to use npm and not manually change `package-lock.json` or anything dodgy like that.

    &quot;devDependencies&quot;: {
      &quot;lerna&quot;: &quot;3.3.2&quot;,
    },
    &quot;resolutions&quot;: {
      &quot;@lerna/publish&quot;: &quot;3.3.2&quot;
    }

npm equivalent of yarn resolutions?

I&#39;m a newbie in Angular. I used `angular-cli` to learn about angular and I found the files `tsconfig.json` and `tsconfig.app.json`. Both of these are typescript related and I found [this link][1] useful.

But why two such files has been used? Why can&#39;t the configurations in these two files be combined in one file? Please help me figure this out.


  [1]: https://stackoverflow.com/questions/48798431/use-of-tsconfig-app-json

Difference between tsconfig.json and tsconfig.app.json files in Angular

I&#39;ve got a problem with my build process in relation to my React app.

I always get the following error:

**Module not found: Error: Can&#39;t resolve &#39;core-js/es6&#39;**

if I use this in a polyfill.js:

**import &#39;core-js/es6&#39;;**

That is my package.json:


&lt;!-- begin snippet: js hide: false console: true babel: false --&gt;

&lt;!-- language: lang-js --&gt;

    {
      &quot;name&quot;: &quot;test&quot;,
      &quot;version&quot;: &quot;1.0.0&quot;,
      &quot;main&quot;: &quot;index.js&quot;,
      &quot;license&quot;: &quot;MIT&quot;,
      &quot;private&quot;: true,
      &quot;devDependencies&quot;: {
        &quot;@babel/core&quot;: &quot;^7.4.0&quot;,
        &quot;@babel/preset-env&quot;: &quot;^7.4.2&quot;,
        &quot;@babel/preset-react&quot;: &quot;^7.0.0&quot;,
        &quot;@babel/runtime&quot;: &quot;^7.4.2&quot;,
        &quot;babel-loader&quot;: &quot;^8.0.5&quot;,
        &quot;babel-preset-es2015&quot;: &quot;^6.24.1&quot;,
        &quot;copy-webpack-plugin&quot;: &quot;^5.0.2&quot;,
        &quot;css-hot-loader&quot;: &quot;^1.4.4&quot;,
        &quot;eslint&quot;: &quot;5.15.3&quot;,
        &quot;eslint-config-airbnb&quot;: &quot;^17.1.0&quot;,
        &quot;eslint-loader&quot;: &quot;^2.1.2&quot;,
        &quot;eslint-plugin-import&quot;: &quot;2.16.0&quot;,
        &quot;eslint-plugin-jsx-a11y&quot;: &quot;6.2.1&quot;,
        &quot;eslint-plugin-react&quot;: &quot;7.12.4&quot;,
        &quot;file-loader&quot;: &quot;^3.0.1&quot;,
        &quot;node-sass&quot;: &quot;^4.11.0&quot;,
        &quot;prettier&quot;: &quot;^1.16.4&quot;,
        &quot;react-hot-loader&quot;: &quot;4.8.0&quot;,
        &quot;sass-loader&quot;: &quot;^7.1.0&quot;,
        &quot;webpack&quot;: &quot;^4.29.6&quot;,
        &quot;webpack-cli&quot;: &quot;^3.3.0&quot;,
        &quot;webpack-dev-server&quot;: &quot;^3.2.1&quot;
      },
      &quot;dependencies&quot;: {
        &quot;axios&quot;: &quot;^0.18.0&quot;,
        &quot;core-js&quot;: &quot;^3.0.0&quot;,
        &quot;prop-types&quot;: &quot;^15.7.2&quot;,
        &quot;react&quot;: &quot;^16.8.5&quot;,
        &quot;react-dom&quot;: &quot;^16.8.5&quot;,
        &quot;react-redux&quot;: &quot;^6.0.1&quot;,
        &quot;react-string-replace&quot;: &quot;^0.4.1&quot;,
        &quot;redux&quot;: &quot;^4.0.1&quot;,
        &quot;slick-carousel&quot;: &quot;^1.8.1&quot;
      },
      &quot;scripts&quot;: {
        &quot;dev&quot;: &quot;webpack-dev-server --hot&quot;,
        &quot;build&quot;: &quot;webpack --colors --profile --progress --env.mode production&quot;,
        &quot;lint&quot;: &quot;eslint ./src/ --ext .js,.jsx&quot;
      }
    }

&lt;!-- end snippet --&gt;

Can someone help here?

Module not found: Error: Can&#39;t resolve &#39;core-js/es6&#39;

I was asked this in an interview. I could not answer.

    &quot;browserslist&quot;: [
    &quot;&gt;0.2%&quot;,
    &quot;not dead&quot;,
    &quot;not ie &lt;= 11&quot;,
    &quot;not op_mini all&quot;
    ]

I can see that Its an array.
&quot;not ie &lt;=11&quot; means will not run on lower than Internet Explorer v11
&quot;op_mini&quot; must be related to Opera mini.

But I want to know why it is required.

What is the significance of browserslist in package.json created by create-react-app

I&#39;ve got an **ApolloServer** project that&#39;s giving me trouble, so I thought I might update it and ran into issues when using the latest Babel. My &quot;index.js&quot; is:

    require(&#39;dotenv&#39;).config()
    import {startServer} from &#39;./server&#39;
    startServer()

And when I run it I get the error

```lang-none
SyntaxError: Cannot use import statement outside a module
```

First I tried doing things to convince TPTB* that this was a module (with no success). So I changed the &quot;**import**&quot; to a &quot;**require**&quot; and this worked.

But now I have about two dozen &quot;**imports**&quot; in other files giving me the same error.

*I&#39;m sure the root of my problem is that I&#39;m not even sure what&#39;s complaining about the issue. I sort of assumed it was Babel 7 (since I&#39;m coming from Babel 6 and I had to change the presets) but I&#39;m not 100% sure.

Most of what I&#39;ve found for solutions don&#39;t seem to apply to straight Node. Like this one here:

*https://stackoverflow.com/questions/47632562/es6-module-import-giving-uncaught-syntaxerror-unexpected-identifier/47633417#47633417*

Says it was resolved by adding &quot;type=module&quot; but this would typically go in the HTML, of which I have none. I&#39;ve also tried using my project&#39;s old presets:

    &quot;presets&quot;: [&quot;es2015&quot;, &quot;stage-2&quot;],
    &quot;plugins&quot;: []

But that gets me another error: &quot;Error: Plugin/Preset files are not allowed to export objects, only functions.&quot;

Here are the dependencies I started with:

    &quot;dependencies&quot;: {
    &quot;@babel/polyfill&quot;: &quot;^7.6.0&quot;,
    &quot;apollo-link-error&quot;: &quot;^1.1.12&quot;,
    &quot;apollo-link-http&quot;: &quot;^1.5.16&quot;,
    &quot;apollo-server&quot;: &quot;^2.9.6&quot;,
    &quot;babel-preset-es2015&quot;: &quot;^6.24.1&quot;,








SyntaxError: Cannot use import statement outside a module

I&#39;m running into an issue with yarn when I change my nvm version of node. 
I noticed when I check my ~/.nvm folder I see two node versions. 

 - v8.11.0  
 - v8.11.3.


I installed yarn globally. using **npm install -g yarn** when I was using v8.11.0. 

I can see yarn in my 

    .nvm/versions/node/v8.11.0

But when I switch to nvm v8.11.3 or set my nvm alias default to v8.11.3  
Yarn is no longer available. I tried doing a global install again hoping it would add it to my v8.11.3 folder but it keeps trying to add it to v8.11.0

I&#39;ve even deleted folder v8.11.0 but it just recreates it when I run npm install -g yarn

How can I get it to install so I can use yarn using any node version switch in nvm



  

Yarn not installing in nvm version node version

I tried to install [Yarn](https://yarnpkg.com/lang/en/) and when I used the `yarn` command I got:

    00h00m00s 0/0: : ERROR: There are no scenarios; must have at least one.

my `yarn --version` is `0.32`. Why doesn&#39;t it work?

Yarn ERROR: There are no scenarios; must have at least one

What does `yarn build` command do ? 
Are `yarn build` and `npm build` the same? If not what&#39;s the difference?



Content Type	Original Author	Original Content on Stackoverflow
Question	rap-2-h	View Question on Stackoverflow
Solution 1 - Javascript	Quentin	View Answer on Stackoverflow
Solution 2 - Javascript	Gabe M	View Answer on Stackoverflow

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