Publish Your First Node Module

2017-03-29 · 3 min read

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