Publish Your First Node Module

Publish Your First Node Module

Pre-requisite

• Install Nodejs.
• Create an account on GitHub & NPM.
• Basic knowledge of JS & git.

NPM configuration

After installing nodejs and creating npm account, go to the terminal and run these commands.

npm set init.author.name "Pradeep Khileri"
npm set init.author.email "pradeepchoudhary009@gmail.com"
npm set init.author.url "https://prdpx7.github.io"

Let’s create our node module

• before naming your module, check if there is already a node module of same name!.

• here our sample node module’s objective is to extract json data of python package from pypi registry.

• Create project dir and follow these steps.

    mkdir pkgstat #let us name our project 'pkgstat'
    cd pkgstat
    npm init # do as it says and it will create package.json(a configuration file for your node module).
  

• Install dependencies for our project. we will use got module which will be used for making http request and extracting json content from web.

    npm install --save got # this will be installed locally,used only for current project.  
  

• Read more about installing npm packages globally without sudo.
• Write the code for our module in index.js

    'use strict';
    const got = require('got');
    const pypi = "https://pypi.python.org/pypi/pkg_name/json";
    function extractMetaData(jsonData, language){
        var pkgMeta = {};
        if(language == 'python'){
             pkgMeta.name = jsonData.info.name;
            pkgMeta.author = jsonData.info.author;
            pkgMeta.description = jsonData.info.summary;
            pkgMeta.url = jsonData.info.package_url;
            pkgMeta.source = jsonData.info.home_page;
            pkgMeta.license = jsonData.info.license;
            pkgMeta.version = jsonData.info.version;
        }
        pkgMeta.status = 200;
        return pkgMeta;
    }
    function setpkgURL(name,language){
        language = language.toLowerCase();
        var url = "";
        if(language == 'python'){
            url = pypi.replace('pkg_name', name);
        }
        else url = "language not supported"; //'got' will handle invalid http request.
        return url;
    }
    module.exports = (name,language) => {
        const url = setpkgURL(name, language);
        const headers = {'User-Agent':'got node module'};
        return got(url, {json:true, headers})
            .then(resp=>{
                return extractMetaData(resp.body, language);
            })
            .catch(err =>{
                return {status:404};
            })    
    }
  

Writing Test for our Module

• testing is important because otherwise you have to manually test it again and again in node(repl) after making some changes in module.
• other developers can also test your module with npm test without headache.
• it’s a good habit, so shut up and write tests for your node module.
• you can use mocha, ava or any other node testing module.(we will use ava).

    npm install -g ava
    ava --init #make sure you are in our project directory where our module resides.
  

• write your test in test.js

    import test from 'ava';
    import pkgstat from '.';
    test('cleanslate pkg in python(pip)', async t =>{
        const data = await pkgstat('cleanslate','python');
        t.is(data.author,'Pradeep Khileri');//matching response(since we know the returned json object(data) contents).
    })
    test('somePkgWhichDoesNotExist in SomeLanguageWhichDoesNotExist', async t =>{
        const data = await pkgstat('somePkgWhichDoesNotExist', 'SomeLanguageWhichDoesNotExist');
        t.is(data.status, 404);
    })
  

• run this test script.

    npm test # it will show which test was passed and which one didn't 
  

• write documentation for your node module.
  • guide on writing markdown.
  • write your documentation in readme.md file.
  • this is sample documentation of our node module.
• final project structure(more or less) will look like this.

    projectDirOfOurNodeModule
    |__node_modules/
    |__readme.md
    |__index.js
    |__test.js
    |__license
    |__package.json
  

Publishing our node module.

• Publish your module to NPM (make sure you’re in project directory).

  npm login 
  # fill out username,password and email
  npm publish
  

• Create a github repo and push your code.
• you don’t want to push node_modules/ to github because these dependencies will be installed when someone will install your module.
• use tool like GiG for generating .gitignore files for your project.
• read more about github.

Final Note

• this is just a smaller version of pkgstat module.
• the full source code of pkgstat is here.
• other useful links -
  • an awesome tutorial on node
  • more about npm
  • publishing node modules
  • Node Module Patterns
  • collection of resources on nodejs