index.js

// Custom Docusaurus plugin to inject Segment analytics
function pluginSegment(context, options = {}) {
  const isProd = process.env.NODE_ENV === "production" || options.allowedInDev;
  const segmentPublicWriteKey = options.segmentPublicWriteKey;

  if (!segmentPublicWriteKey) {
    console.warn('Segment plugin: No write key provided. Analytics will not be initialized.');
    return { name: 'docusaurus-plugin-segment' };
  }

  return {
    name: 'docusaurus-plugin-segment',

    getClientModules() {
      return isProd ? [require.resolve('./analytics-page'), require.resolve('./data-attribute-tracking')] : [];
    },

    injectHtmlTags() {
      if (!isProd) {
        return {};
      }

      return {
        headTags: [
          {
            tagName: 'script',
            innerHTML: `
              !function(){var i="analytics",analytics=window[i]=window[i]||[];if(!analytics.initialize)if(analytics.invoked)window.console&&console.error&&console.error("Segment snippet included twice.");else{analytics.invoked=!0;analytics.methods=["trackSubmit","trackClick","trackLink","trackForm","pageview","identify","reset","group","track","ready","alias","debug","page","screen","once","off","on","addSourceMiddleware","addIntegrationMiddleware","setAnonymousId","addDestinationMiddleware","register"];analytics.factory=function(e){return function(){if(window[i].initialized)return window[i][e].apply(window[i],arguments);var n=Array.prototype.slice.call(arguments);if(["track","screen","alias","group","page","identify"].indexOf(e)>-1){var c=document.querySelector("link[rel='canonical']");n.push({__t:"bpc",c:c&&c.getAttribute("href")||void 0,p:location.pathname,u:location.href,s:location.search,t:document.title,r:document.referrer})}n.unshift(e);analytics.push(n);return analytics}};for(var n=0;n<analytics.methods.length;n++){var key=analytics.methods[n];analytics[key]=analytics.factory(key)}analytics.load=function(key,n){var t=document.createElement("script");t.type="text/javascript";t.async=!0;t.setAttribute("data-global-segment-analytics-key",i);t.src="https://cdn.segment.com/analytics.js/v1/" + key + "/analytics.min.js";var r=document.getElementsByTagName("script")[0];r.parentNode.insertBefore(t,r);analytics._loadOptions=n};analytics._writeKey="${segmentPublicWriteKey}";;analytics.SNIPPET_VERSION="5.2.0";
              analytics.load("${segmentPublicWriteKey}");
              analytics.page();
              }}();
            `,
          },
        ],
      };
    },
  };
}

module.exports = pluginSegment;