use raf to impl a more accurate timer and replay events async

src/replay/index.ts

@@ -1,62 +1,131 @@
 import { rebuild } from 'rrweb-snapshot';
 import { mirror } from '../utils';
-import { event, EventType, incrementalData, IncrementalSource } from '../types';
+import later from './timer';
+import {
+  EventType,
+  incrementalData,
+  IncrementalSource,
+  fullSnapshotEvent,
+  eventWithTime,
+} from '../types';
 import eventsStr from './events';
 
-const events: event[] = JSON.parse(eventsStr);
+const _events: eventWithTime[] = JSON.parse(eventsStr);
 
-function applyIncremental(d: incrementalData) {
-  switch (d.source) {
-    case IncrementalSource.Mutation:
-    case IncrementalSource.MouseMove:
-    case IncrementalSource.MouseInteraction:
-      break;
-    case IncrementalSource.Scroll:
-      // TODO: maybe element
-      window.scrollTo({
-        top: d.y,
-        left: d.x,
-        behavior: 'smooth',
-      });
-      break;
-    case IncrementalSource.ViewportResize:
-    case IncrementalSource.Input:
-    default:
+class Replayer {
+  private events: eventWithTime[] = [];
+  private wrapper: HTMLDivElement;
+  private iframe: HTMLIFrameElement;
+  private mouse: HTMLDivElement;
+  private startTime: number = 0;
+
+  constructor(events: eventWithTime[]) {
+    this.events = events;
   }
-}
 
-function replay() {
-  const iframe = document.createElement('iframe');
-  for (const event of events) {
-    switch (event.type) {
-      case EventType.DomContentLoaded:
+  public play() {
+    this.setupDom();
+    for (const event of this.events) {
+      switch (event.type) {
+        case EventType.DomContentLoaded:
+          this.startTime = event.timestamp;
+          break;
+        case EventType.Load:
+          this.iframe.width = `${event.data.width}px`;
+          this.iframe.height = `${event.data.height}px`;
+          break;
+        case EventType.FullSnapshot:
+          later(() => {
+            this.rebuildFullSnapshot(event);
+          }, this.getDelay(event));
+          break;
+        case EventType.IncrementalSnapshot:
+          later(() => {
+            this.applyIncremental(event.data);
+          }, this.getDelay(event));
+          break;
+        default:
+      }
+    }
+  }
+
+  private setupDom() {
+    this.wrapper = document.createElement('div');
+    this.wrapper.classList.add('replayer-wrapper');
+    document.body.appendChild(this.wrapper);
+
+    this.mouse = document.createElement('div');
+    this.mouse.classList.add('replayer-mouse');
+    this.wrapper.appendChild(this.mouse);
+
+    this.iframe = document.createElement('iframe');
+    this.wrapper.appendChild(this.iframe);
+  }
+
+  private getDelay(event: eventWithTime): number {
+    if (
+      event.type === EventType.IncrementalSnapshot &&
+      event.data.source === IncrementalSource.MouseMove
+    ) {
+      const firstOffset = event.data.positions[0].timeOffset;
+      // timeoffset is a negative offset to event.timestamp
+      const firstTimestamp = event.timestamp + firstOffset;
+      event.data.positions = event.data.positions.map(p => {
+        return {
+          ...p,
+          timeOffset: p.timeOffset - firstOffset,
+        };
+      });
+      return firstTimestamp - this.startTime;
+    }
+    return event.timestamp - this.startTime;
+  }
+
+  private rebuildFullSnapshot(event: fullSnapshotEvent) {
+    const [doc, map] = rebuild(event.data.node);
+    mirror.map = map;
+    if (doc) {
+      this.iframe.contentDocument!.open();
+      // https://developer.mozilla.org/en-US/docs/Web/API/Element/innerHTML
+      this.iframe.contentDocument!.write(
+        (doc as Document).documentElement.outerHTML
+          .replace(/&/g, '&')
+          .replace(/&lt;/g, '<')
+          .replace(/&gt;/g, '>'),
+      );
+      this.iframe.contentDocument!.close();
+    }
+  }
+
+  private applyIncremental(d: incrementalData) {
+    switch (d.source) {
+      case IncrementalSource.Mutation:
         break;
-      case EventType.Load:
-        iframe.width = `${event.data.width}px`;
-        iframe.height = `${event.data.height}px`;
+      case IncrementalSource.MouseMove:
+        d.positions.forEach(p => {
+          later(() => {
+            this.mouse.style.left = `${p.x}px`;
+            this.mouse.style.top = `${p.y}px`;
+          }, p.timeOffset);
+        });
         break;
-      case EventType.FullSnapshot:
-        const [doc, map] = rebuild(event.data.node);
-        mirror.map = map;
-        if (doc) {
-          document.body.appendChild(iframe);
-          iframe.contentDocument!.open();
-          // https://developer.mozilla.org/en-US/docs/Web/API/Element/innerHTML
-          iframe.contentDocument!.write(
-            (doc as Document).documentElement.outerHTML
-              .replace(/&amp;/g, '&')
-              .replace(/&lt;/g, '<')
-              .replace(/&gt;/g, '>'),
-          );
-          iframe.contentDocument!.close();
-        }
+      case IncrementalSource.MouseInteraction:
         break;
-      case EventType.IncrementalSnapshot:
-        applyIncremental(event.data);
+      case IncrementalSource.Scroll:
+        // TODO: maybe element
+        this.iframe.contentWindow!.scrollTo({
+          top: d.y,
+          left: d.x,
+          behavior: 'smooth',
+        });
         break;
+      case IncrementalSource.ViewportResize:
+      case IncrementalSource.Input:
       default:
     }
   }
 }
 
-export default replay;
+const replayer = new Replayer(_events);
+
+export default replayer;

src/replay/styles/style.css

@@ -0,0 +1,10 @@
+.replayer-wrapper {
+  position: relative;
+}
+.replayer-mouse {
+  position: absolute;
+  width: 20px;
+  height: 20px;
+  border-radius: 10px;
+  background: thistle;
+}

src/replay/timer.ts

@@ -0,0 +1,17 @@
+const FRAME_MS = 16;
+
+function later(cb: () => void, delayMs: number) {
+  const now = performance.now();
+
+  function check(step: number) {
+    if (step - now > delayMs - FRAME_MS) {
+      cb();
+    } else {
+      requestAnimationFrame(check);
+    }
+  }
+
+  requestAnimationFrame(check);
+}
+
+export default later;