feat (@jitsu/js): Add defaultPayloadContext to include default cont…

libs/jitsu-js/__tests__/node/nodejs.test.ts

@@ -214,6 +214,33 @@ describe("Test Jitsu NodeJS client", () => {
     expect((p.body.anonymousId ?? "").length).toBeGreaterThan(0);
   });
 
+  test("test defaultPayloadContext", async () => {
+    const config = {
+      host: server.baseUrl,
+      writeKey: "key:secret",
+      debug: true,
+      defaultPayloadContext: {
+        awesomeIdentifier: "awesome-identifier",
+        awesome: {
+          nestedKey: "awesome-key",
+        },
+      },
+    };
+    const client = jitsuAnalytics(config);
+    expect(requestLog.length).toBe(0);
+    await client.identify("myUserId", { email: "[email protected]" });
+    await client.group("myGroupId", { name: "myGroupId" });
+    await client.track("myEvent", { prop1: "value1" });
+    await new Promise(resolve => setTimeout(resolve, 1000));
+    expect(requestLog.length).toBe(3);
+    expect(requestLog[0].body.context.awesomeIdentifier).toBe("awesome-identifier");
+    expect(requestLog[0].body.context.awesome.nestedKey).toBe("awesome-key");
+    expect(requestLog[1].body.context.awesomeIdentifier).toBe("awesome-identifier");
+    expect(requestLog[1].body.context.awesome.nestedKey).toBe("awesome-key");
+    expect(requestLog[2].body.context.awesomeIdentifier).toBe("awesome-identifier");
+    expect(requestLog[2].body.context.awesome.nestedKey).toBe("awesome-key");
+  });
+
   test("node js", async () => {
     const jitsu: AnalyticsInterface = jitsuAnalytics({
       writeKey: "key:secret",

libs/jitsu-js/src/analytics-plugin.ts

@@ -39,6 +39,7 @@ const defaultConfig: Required<JitsuOptions> = {
   s2s: undefined,
   idEndpoint: undefined,
   errorPolicy: "log",
+  defaultPayloadContext: {},
   privacy: {
     dontSend: false,
     disableUserIds: false,
@@ -445,7 +446,10 @@ function adjustPayload(
     properties.path = fixPath(urlPath(targetUrl));
   }
 
-  const customContext = payload.properties?.context || payload.options?.context || {};
+  const customContext = deepMerge(
+    config.defaultPayloadContext,
+    payload.properties?.context || payload.options?.context || {}
+  );
   delete payload.properties?.context;
   const referrer = runtime.referrer();
   const context: AnalyticsClientEvent["context"] = {

types/protocols/analytics.d.ts

@@ -346,6 +346,15 @@ export type JitsuOptions = {
    * To enable debug logging
    */
   debug?: boolean;
+  /**
+   * Default payload context to be included in all requests.
+   * These attributes are merged with the request-specific payload context,
+   * allowing common or global data (e.g., browser timezone, some extra user identifier)
+   * to be automatically included to every request.
+   *
+   * The context can be a nested structure.
+   */
+  defaultPayloadContext?: Record<string, JSONValue>;
   /**
    * Explicitly specify cookie domain. If not set, cookie domain will be set to top level
    * of the current domain. Example: if JS lives on "app.example.com", cookie domain will be