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docs/recipes/custom-event.md

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+# Custom Event
+
+You may need to record some custom events along with the rrweb events, and let them be played as other events. The custom event API was designed for this.
+
+After starting the recording, we can call the `record.addCustomEvent` API to add a custom event.
+
+```js
+// start recording
+rrweb.record({
+  emit(event) {
+    ...
+  }
+})
+
+// record some custom events at any time
+rrweb.record.addCustomEvent('submit-form', {
+  name: 'Adam',
+  age: 18
+})
+rrweb.record.addCustomEvent('some-error', {
+  error
+})
+```
+
+`addCustomEvent` accepts two parameters. The first one is a string-type `tag`, while the second one is an any-type `payload`.
+
+During the replay, we can add an event listener to custom events, or configure the style of custom events in rrweb-player's timeline.
+
+**Listen to custom events**
+
+```js
+const replayer = new rrweb.Replayer(events);
+
+replayer.on('custom-event', (event) => {
+  console.log(event.tag, event.payload);
+});
+```
+
+**Display in rrweb-player**
+
+```js
+new rrwebPlayer({
+  target: document.body,
+  props: {
+    events,
+    // configure the color of tag which will be displayed on the timeline
+    tags: {
+      'submit-form': '#21e676',
+      'some-error': 'red',
+    },
+  },
+});
+```