feat: support passing custom getUserId function

README.md

@@ -86,6 +86,23 @@ Finally, in case you are using banners and want to have further control on the a
 </div>
 ```
 
+### Overriding default User ID behavior
+
+If you want to pass your own User ID when sending events, you can do so by overiding the `getUserID()` function which is
+responsible for retrieving a unique identifier for the user. It should additionally set a new value if none is found. This function should return a string with the User ID (as a string) passed in the events.
+
+```javascript
+window.TS = {
+	token: "<YOUR-TOPSORT.JS-TOKEN>",
+	getUserId() {
+		// globalUserId is the user id you would like to pass to the analytics
+		// generateAndStoreUserId is a function that generates a new user id and stores it in a cookie/local storage
+		return globalUserId ?? generateAndStoreUserId();
+	},
+};
+```
+
+```html
 # Troubleshooting
 
 ## I see `Uncaught Error: Mismatched anonymous define() module` in the browser console

src/detector.custom-getuserid.test.ts

@@ -0,0 +1,38 @@
+import { expect, test } from "vitest";
+
+test("support custom getUserId function", async () => {
+  window.TS = {
+    token: "token",
+    getUserId: () => {
+      return "custom-user-id";
+    },
+  };
+  const events: any[] = [];
+  window.addEventListener("topsort", (e) => {
+    events.push((e as any).detail);
+  });
+  document.body.innerHTML = `
+    <div id="product" data-ts-product="product-id-click-1" data-ts-resolved-bid="1247eaae-63a1-4c20-9b52-9efdcdef3095"></div>
+  `;
+  await import("./detector");
+
+  document.getElementById("product")?.click();
+  expect(events).toMatchObject([
+    {
+      type: "Impression",
+      page: "/",
+      product: "product-id-click-1",
+      bid: "1247eaae-63a1-4c20-9b52-9efdcdef3095",
+      id: expect.stringMatching(/[\d.a-zA-Z-]+/),
+      uid: "custom-user-id",
+    },
+    {
+      type: "Click",
+      page: "/",
+      product: "product-id-click-1",
+      bid: "1247eaae-63a1-4c20-9b52-9efdcdef3095",
+      id: expect.stringMatching(/[\d.a-zA-Z-]+/),
+      uid: "custom-user-id",
+    },
+  ]);
+});

src/detector.ts

@@ -1,6 +1,6 @@
-import { type Config, Entity, TopsortClient, Event as TopsortEvent } from "@topsort/sdk";
+import { type Config, type Entity, TopsortClient, type Event as TopsortEvent } from "@topsort/sdk";
 import { version } from "../package.json";
-import { ProcessorResult, Queue } from "./queue";
+import { type ProcessorResult, Queue } from "./queue";
 import { truncateSet } from "./set";
 import { BidStore } from "./store";
 
@@ -17,7 +17,7 @@
  * just be a random number;
  */
 function generateId(): string {
-  return window.URL.createObjectURL?.(new Blob()).split("/").pop() || Math.random() + "";
+  return window.URL.createObjectURL?.(new Blob()).split("/").pop() || `${Math.random()}`;
 }
 
 let globalUserId: string | undefined;
@@ -39,7 +39,7 @@
 function setUserIdCookie(id: string): void {
   const cookieName = window.TS.cookieName || "tsuid";
   globalUserId = id;
-  document.cookie = cookieName + "=" + id + ";max-age=31536000";
+  document.cookie = `${cookieName}=${id};max-age=31536000`;
 }
 
 function resetUserId(): string {
@@ -49,13 +49,15 @@
 }
 
 window.TS.setUserId = setUserIdCookie;
-window.TS.getUserId = getUserId;
+if (typeof window.TS.getUserId !== "function") {
+  window.TS.getUserId = getUserId;
+}
 window.TS.resetUserId = resetUserId;
 
 // Based on https://stackoverflow.com/a/25490531/1413687
 function getUserIdCookie(): string | undefined {
   const cookieName = window.TS.cookieName || "tsuid";
-  const regex = new RegExp("(^|;)\\s*" + cookieName + "\\s*=\\s*([^;]+)");
+  const regex = new RegExp(`(^|;)\\s*${cookieName}\\s*=\\s*([^;]+)`);
   return regex.exec(document.cookie)?.pop();
 }
 
@@ -212,7 +214,7 @@
   let product = node.dataset.tsProduct;
   let bid = node.dataset.tsResolvedBid;
   let additionalProduct: string | undefined = undefined;
-  if (bid == "inherit" && product && (type == "Click" || type == "Impression")) {
+  if (bid === "inherit" && product && (type === "Click" || type === "Impression")) {
     bid = bidStore.get();
     additionalProduct = product;
     product = undefined;
@@ -225,7 +227,7 @@
     t: Date.now(),
     page: getPage(),
     id: generateId(),
-    uid: getUserId(),
+    uid: window.TS.getUserId() ?? getUserId(),
   };
   if (type === "Purchase") {
     event.items = JSON.parse(node.dataset.tsItems || "[]");