Buffer modifications to virtual stylesheets (#618)

* Fix sheet insertion

Restore skip duration

Use virtualStyleRulesMap to re-populate stylesheet on Flush event

Clear virtualStyleRulesMap after flush applied

* Support rule deletion in virtual processing

* Simply restoreNodeSheet with early aborts

* Encountered a bug where firstFullSnapshot was played twice because timer was immediately started and reached the snapshot before the setTimeout returned

* Ignoring a FullSnapshot needs to be a one-time only thing, as otherwise we'll ignore it after scrubbing (restarting play head at a particular time). This is a problem if mutations have altered the player state, and we try to replay those mutations, so we e.g. try to remove an element that has already been removed because we haven't reset the FullSnapshot state

* Some `npm run typings` related fixups

* add basic html snapshot functionality

* move restoreNodeSheet to it's own module

* Refactor virtual style rules to buffer changes.
Only applies changes on flush.

`virtualStyleRulesMap` now works with strings instead of CSSRules.
CSSRules can only be via made `.insertRule` on CSSStyleSheet in most browsers.
And `new CSSStyleSheet()` only works in Chrome currently.

* remove unused code

* move VirtualStyleRules from CSSRule to string in tests

* correct paths for tests

* naming

* create and restore style snapshots for virtual nodes

* update replayer snapshot

* move storeCSSRules to virtual-styles.ts

* try/catch access to .sheet in case of access errors

* clean up tests

Co-authored-by: Vladimir Milenko <vladimir.milenko@uber.com>
Co-authored-by: Eoghan Murray <eoghan@getthere.ie>

test/replayer.test.ts

@@ -6,6 +6,7 @@ import * as puppeteer from 'puppeteer';
 import { expect } from 'chai';
 import { Suite } from 'mocha';
 import {
+  assertDomSnapshot,
   launchPuppeteer,
   sampleEvents as events,
   sampleStyleSheetRemoveEvents as stylesheetRemoveEvents,
@@ -146,11 +147,35 @@ describe('replayer', function (this: ISuite) {
       replayer.play(1500);
       replayer['timer']['actions'].length;
     `);
+
     expect(actionLength).to.equal(
       styleSheetRuleEvents.filter(
         (e) => e.timestamp - styleSheetRuleEvents[0].timestamp >= 1500,
       ).length,
     );
+
+    await assertDomSnapshot(
+      this.page,
+      __filename,
+      'style-sheet-rule-events-play-at-1500',
+    );
+  });
+
+  it('should apply fast forwarded StyleSheetRules that where added', async () => {
+    await this.page.evaluate(
+      `events = ${JSON.stringify(styleSheetRuleEvents)}`,
+    );
+    const result = await this.page.evaluate(`
+      const { Replayer } = rrweb;
+      const replayer = new Replayer(events);
+      replayer.pause(1500);
+      const rules = [...replayer.iframe.contentDocument.styleSheets].map(
+        (sheet) => [...sheet.rules],
+      ).flat();
+      rules.some((x) => x.selectorText === '.css-added-at-1000-deleted-at-2500');
+    `);
+
+    expect(result).to.equal(true);
   });
 
   it('can handle removing style elements', async () => {
@@ -168,6 +193,47 @@ describe('replayer', function (this: ISuite) {
         (e) => e.timestamp - stylesheetRemoveEvents[0].timestamp >= 2500,
       ).length,
     );
+
+    await assertDomSnapshot(
+      this.page,
+      __filename,
+      'style-sheet-remove-events-play-at-2500',
+    );
+  });
+
+  it('can fast forward past StyleSheetRule deletion on virtual elements', async () => {
+    await this.page.evaluate(
+      `events = ${JSON.stringify(styleSheetRuleEvents)}`,
+    );
+    const actionLength = await this.page.evaluate(`
+      const { Replayer } = rrweb;
+      const replayer = new Replayer(events);
+      replayer.play(2500);
+      replayer['timer']['actions'].length;
+    `);
+
+    await assertDomSnapshot(
+      this.page,
+      __filename,
+      'style-sheet-rule-events-play-at-2500',
+    );
+  });
+
+  it('should delete fast forwarded StyleSheetRules that where removed', async () => {
+    await this.page.evaluate(
+      `events = ${JSON.stringify(styleSheetRuleEvents)}`,
+    );
+    const result = await this.page.evaluate(`
+      const { Replayer } = rrweb;
+      const replayer = new Replayer(events);
+      replayer.pause(3000);
+      const rules = [...replayer.iframe.contentDocument.styleSheets].map(
+        (sheet) => [...sheet.rules],
+      ).flat();
+      rules.some((x) => x.selectorText === '.css-added-at-1000-deleted-at-2500');
+    `);
+
+    expect(result).to.equal(false);
   });
 
   it('can stream events in live mode', async () => {