Creating a Node.js Packaged Module

To create a Node.js Packaged Module, you need to create the functionality in JavaScript, define the package using a package.json file, and then either publish it to the registry or package it for local use.

The following steps take you through the process of building a Node.js Packaged Module, using a module called censorify that will accept text and replace certain words with asterisks:

1. Create a project folder named .../censorify. This will be the root of the package.

2. Inside that folder, create a file named censortext.js.

3. Add the code from Listing 3.1 to censortext.js. Most of the code is just basic JavaScript, but note that lines 18–20 export the functions censor(), addCensoredWord(), and getCensoredWords(). exports.censor is required for Node.js applications using this module to have access to the censor() function as well as the other two functions.

Listing 3.1 censortext.js: Node.js module code that implements a simple censor function and exports it for other modules using the package

Click here to view code image

01 var censoredWords = ["sad", "bad", "mad"];
02 var customCensoredWords = [];
03 function censor(inStr) {
04   for (idx in censoredWords) {
05     inStr = inStr.replace(censoredWords[idx], "****");
06   }
07   for (idx in customCensoredWords) {
08     inStr = inStr.replace(customCensoredWords[idx], "****");
09   }
10   return inStr;
11 }
12 function addCensoredWord(word){
13   customCensoredWords.push(word);
14 }
15 function getCensoredWords(){
16   return censoredWords.concat(customCensoredWords);
17 }
18 exports.censor = censor;
19 exports.addCensoredWord = addCensoredWord;
20 exports.getCensoredWords = getCensoredWords;

4. You need a package.json file that will be used to generate the Node.js Packaged Module, so create a package.json file in the .../censorify folder. Then add contents similar to Listing 3.2. Specifically, you need to add at least the name, version, and main directives. The main directive needs to be the name of the main JavaScript module that will be loaded—in this case censortext. Note that the .js is not required; Node.js automatically searches for the .js extension.

Listing 3.2 package.json: Package definition that defines the Node.js module

Click here to view code image

01 {
02   "author": "Brad Dayley",
03   "name": "censorify",
04   "version": "0.1.1",
05   "description": "Censors words out of text",
06   "main": "censortext",
07   "dependencies": {},
08   "engines": {
09       "node": "*"
10   }
11 }

5. Create a file named README.md in the .../censorify folder. Place in this file any readme instructions you would like.

6. Navigate to the .../censorify folder in a console window and execute the following command to build a local package module:

npm pack

The npm pack command creates a censorify-0.1.1.tgz file in the .../censorify folder. This is your first Node.js Packaged Module.