https://www.canterbury.co.uk/cpresources/f99b9ba9/ga-algolia-interceptor.js

1/**
2 * Algolia Request Interceptor (early-load)
3 *
4 * This script MUST load before the Algolia JS client initialises.
5 * It patches both fetch and XMLHttpRequest to capture Algolia search
6 * responses and buffer them for the GA event tracking registry to
7 * process once it loads.
8 *
9 * Buffered responses are stored in window.__gaAlgoliaBuffer and
10 * consumed by registerAlgoliaInterceptor() in ga-event-tracking-registry.js.
11 */
12(function () {
13  window.__gaAlgoliaBuffer = [];
14
15  function isAlgoliaRequest(url) {
16    return typeof url === "string" && (url.indexOf("algolianet") !== -1 || url.indexOf("algolia.net") !== -1);
17  }
18
19  function getAlgoliaRequestType(url) {
20    if (!isAlgoliaRequest(url)) {
21      return null;
22    }
23    if (url.indexOf("/recommendations") !== -1) {
24      return "recommendation";
25    }
26    return "search";
27  }
28
29  // --- Patch fetch ---
30  var originalFetch = window.fetch;
31  window.fetch = function () {
32    var url = arguments[0];
33    var opts = arguments[1];
34    var urlStr = typeof url === "string" ? url : (url && url.url ? url.url : "");
35
36    var requestType = getAlgoliaRequestType(urlStr);
37    if (!requestType) {
38      return originalFetch.apply(this, arguments);
39    }
40
41    var fetchBody = opts && opts.body ? opts.body : null;
42
43    return originalFetch.apply(this, arguments).then(function (response) {
44      var clone = response.clone();
45      clone.json().then(function (data) {
46        window.__gaAlgoliaBuffer.push({ data: data, body: fetchBody, type: requestType });
47      }).catch(function () {});
48      return response;
49    });
50  };
51
52  // --- Patch XMLHttpRequest ---
53  var originalXHROpen = XMLHttpRequest.prototype.open;
54  var originalXHRSend = XMLHttpRequest.prototype.send;
55
56  XMLHttpRequest.prototype.open = function () {
57    this._gaUrl = arguments[1] || "";
58    return originalXHROpen.apply(this, arguments);
59  };
60
61  XMLHttpRequest.prototype.send = function (body) {
62    var xhr = this;
63    var xhrBody = body;
64
65    var requestType = getAlgoliaRequestType(xhr._gaUrl || "");
66    if (requestType) {
67      xhr.addEventListener("load", function () {
68        try {
69          var data = JSON.parse(xhr.responseText);
70          window.__gaAlgoliaBuffer.push({ data: data, body: xhrBody, type: requestType });
71        } catch (e) {
72          // Silently ignore parse errors
73        }
74      });
75    }
76
77    return originalXHRSend.apply(this, arguments);
78  };
79})();