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· 5 min read
Simon Porritt

jsPlumb uses Statcounter to keep track of what pages in the documentation people are looking at. Recently, at the tail end of the work to migrate to Typescript and release version 5.x of the Community and Toolkit editions, I started using Docusaurus, a super handy static site generator that not only runs on React but has React baked right into it, allowing us to easily embed working demonstrations throughout our docs, or to embed snippets from the api documentation directly into the main documentation via React components. It's a really handy tool, and if you're looking for a static site generator I recommend giving it a look.

note

When I say "Docusaurus" in this post I am talking about v2. I've not used v1.

This is not a post about how great Docusaurus is, though. This is a quick post about a Statcounter plugin I wrote while working on the jsPlumb API documentation. Docusaurus ships with a plugin for Google Analytics, allowing to quickly add support for GA to all the pages on your site, but jsPlumb doesn't use Google Analytics. Statcounter's interface has a pleasing directness to it and gives us all the information we need. A quick look around the internets came up blank on existing Docusaurus/Statcounter integrations, so I wrote a plugin.

Installation#

npm i @jsplumb/docusaurus-plugin-statcounter

Configuration#

First you have to add the plugin to the list of plugins in docusaurus.config.js:

plugins:[      "@jsplumb/docusaurus-plugin-statcounter"  ],

Then you need to configure the plugin via a statCounter block in the themeConfig of your docusaurus.config.js. It takes two arguments, both required:

themeConfig: {    statCounter:{      projectId: "2222222",      securityCode: "2222222"    },    ...}

projectId and securityCode are available in the Statcounter console for the project you wish to target.

Internals#

This is the first plugin I've written for Docusaurus and it doesn't have the most complex requirements, but I was quite impressed with the plugin mechanism. Let's start with the package.json:

{  "main": "src/index.js",  "name": "@jsplumb/docusaurus-plugin-statcounter",  "version": "1.0.0"}

We deliver a basic package with a single entry point.

Bootstrap#

Let's take a look at the first few lines of index.js:


const path = require('path');
module.exports = function (context) {    const {siteConfig} = context;  const {themeConfig} = siteConfig;  const {statCounter} = themeConfig || {};    };

Our module exports a single function that takes a context object, inside of which we can extract the siteConfig, and, from that, the themeConfig, which contains our statCounter settings.

Once we have our statCounter object, we extract the things we need from it, and complain about stuff that is missing:

const {projectId, securityCode} = statCounter;
if (!projectId) {    throw new Error(`The statcounter plugin requires a "projectId" to be set`)}
if (!securityCode) {    throw new Error(`The statcounter plugin requires a "securityCode" to be set`)}

Linking with Statcounter#

Statcounter works by importing a JS file in your document's head, after setting a couple of global variables. Docusaurus makes this very easy for us - all we have to do is declare an injectHtmlTags() method in our plugin:

return {    name: 'docusaurus-plugin-statcounter',
    getClientModules() {      return [path.resolve(__dirname, './statcounter')]    },
    injectHtmlTags() {
      return {        headTags:[          {              tagName:'script',              innerHTML: `                var sc_project="${projectId}";                 var sc_invisible=1;                 var sc_security="${securityCode}";              `          },          {            tagName:'script',            attributes:{              src:"https://www.statcounter.com/counter/counter.js"            }          }        ]      }    }  };

We inject two tags into the head: first we inject a script element and provide its innerHTML - this sets up the global variables. Next, we inject another script, but this time we set its src attribute, so it loads the JS from Statcounter's site. Documentation for injectHtmlTags(..) can be found here.

Tracking page changes#

Given that Docusaurus is an SPA, pages get swapped in and out without new page loads, and Statcounter would be oblivious, were we not to advise it. Fortunately this was also straightforward. Note this block in our plugin's code:

getClientModules() {  return [path.resolve(__dirname, './statcounter')]}

This instructs Docusaurus to load the module found in ./statcounter.js. The source code for that file looks like this:

import ExecutionEnvironment from '@docusaurus/ExecutionEnvironment';
export default (function () {  if (!ExecutionEnvironment.canUseDOM) {    return null;  }
  return {    onRouteUpdate({location}) {      _statcounter.record_pageview()    },  };})();

This module hooks into onRouteUpdate, which I think is perhaps undocumented (for inspiration on this bit I used the Google Analytics plugin).

When a route update event occurs, we call _statcounter.record_pageview(). _statcounter is an object in the global space that was added by Statcounter's JS.

Conclusion#

That's the whole plugin - perhaps 80 lines of code. Very straightforward - it took me about half an hour to write and deploy. Injecting HTML tags is not the only thing you can do with a Docusaurus plugin, though. Take a look through the lifecycle APIs to get a feel for what's possible.

If you want to follow up on this, the source is on Github at https://github.com/jsplumb/docusaurus-plugin-statcounter.