fix(rrweb): Fix some css issues with :hover and rewrite max-device-width

.changeset/rotten-spies-enjoy.md

@@ -0,0 +1,6 @@
+---
+'@amplitude/rrweb': patch
+---
+
+Ensure :hover works on replayer, even if a rule is behind a media query
+Respect the intent behind max-device-width and min-device-width media queries so that their effects are apparent in the replayer context

packages/rrweb-snapshot/src/css.ts

@@ -56,6 +56,11 @@ export interface Node {
   };
 }
 
+export interface NodeWithRules extends Node {
+  /** Array of nodes with the types rule, comment and any of the at-rule types. */
+  rules: Array<Rule | Comment | AtRule>;
+}
+
 export interface Rule extends Node {
   /** The list of selectors of the rule, split on commas. Each selector is trimmed from whitespace and comments. */
   selectors?: string[];
@@ -98,13 +103,11 @@ export interface CustomMedia extends Node {
 /**
  * The @document at-rule.
  */
-export interface Document extends Node {
+export interface Document extends NodeWithRules {
   /** The part following @document. */
   document?: string;
   /** The vendor prefix in @document, or undefined if there is none. */
   vendor?: string;
-  /** Array of nodes with the types rule, comment and any of the at-rule types. */
-  rules?: Array<Rule | Comment | AtRule>;
 }
 
 /**
@@ -118,10 +121,7 @@ export interface FontFace extends Node {
 /**
  * The @host at-rule.
  */
-export interface Host extends Node {
-  /** Array of nodes with the types rule, comment and any of the at-rule types. */
-  rules?: Array<Rule | Comment | AtRule>;
-}
+export type Host = NodeWithRules;
 
 /**
  * The @import at-rule.
@@ -153,11 +153,9 @@ export interface KeyFrame extends Node {
 /**
  * The @media at-rule.
  */
-export interface Media extends Node {
+export interface Media extends NodeWithRules {
   /** The part following @media. */
   media?: string;
-  /** Array of nodes with the types rule, comment and any of the at-rule types. */
-  rules?: Array<Rule | Comment | AtRule>;
 }
 
 /**
@@ -181,11 +179,9 @@ export interface Page extends Node {
 /**
  * The @supports at-rule.
  */
-export interface Supports extends Node {
+export interface Supports extends NodeWithRules {
   /** The part following @supports. */
   supports?: string;
-  /** Array of nodes with the types rule, comment and any of the at-rule types. */
-  rules?: Array<Rule | Comment | AtRule>;
 }
 
 /** All at-rules. */
@@ -205,10 +201,8 @@ export type AtRule =
 /**
  * A collection of rules
  */
-export interface StyleRules {
+export interface StyleRules extends NodeWithRules {
   source?: string;
-  /** Array of nodes with the types rule, comment and any of the at-rule types. */
-  rules: Array<Rule | Comment | AtRule>;
   /** Array of Errors. Errors collected during parsing when option silent is true. */
   parsingErrors?: ParserError[];
 }
@@ -224,7 +218,7 @@ export interface Stylesheet extends Node {
 // https://github.com/visionmedia/css-parse/pull/49#issuecomment-30088027
 const commentre = /\/\*[^*]*\*+([^/*][^*]*\*+)*\//g;
 
-export function parse(css: string, options: ParserOptions = {}) {
+export function parse(css: string, options: ParserOptions = {}): Stylesheet {
   /**
    * Positional.
    */
@@ -932,7 +926,7 @@ function trim(str: string) {
  * Adds non-enumerable parent node reference to each node.
  */
 
-function addParent(obj: Stylesheet, parent?: Stylesheet) {
+function addParent(obj: Stylesheet, parent?: Stylesheet): Stylesheet {
   const isNode = obj && typeof obj.type === 'string';
   const childParent = isNode ? obj : parent;
 

packages/rrweb-snapshot/src/index.ts

@@ -11,7 +11,7 @@ import snapshot, {
 } from './snapshot';
 import rebuild, {
   buildNodeWithSN,
-  addHoverClass,
+  adaptCssForReplay,
   createCache,
 } from './rebuild';
 export * from './types';
@@ -22,7 +22,7 @@ export {
   serializeNodeWithId,
   rebuild,
   buildNodeWithSN,
-  addHoverClass,
+  adaptCssForReplay,
   createCache,
   transformAttribute,
   ignoreAttribute,

packages/rrweb-snapshot/src/rebuild.ts

@@ -1,4 +1,4 @@
-import { parse } from './css';
+import { Rule, Media, NodeWithRules, parse } from './css';
 import {
   serializedNodeWithId,
   NodeType,
@@ -63,9 +63,11 @@ function escapeRegExp(str: string) {
   return str.replace(/[.*+?^${}()|[\]\\]/g, '\\$&'); // $& means the whole matched string
 }
 
+const MEDIA_SELECTOR = /(max|min)-device-(width|height)/;
+const MEDIA_SELECTOR_GLOBAL = new RegExp(MEDIA_SELECTOR.source, 'g');
 const HOVER_SELECTOR = /([^\\]):hover/;
 const HOVER_SELECTOR_GLOBAL = new RegExp(HOVER_SELECTOR.source, 'g');
-export function addHoverClass(cssText: string, cache: BuildCache): string {
+export function adaptCssForReplay(cssText: string, cache: BuildCache): string {
   const cachedStyle = cache?.stylesWithHoverClass.get(cssText);
   if (cachedStyle) return cachedStyle;
 
@@ -78,35 +80,61 @@ export function addHoverClass(cssText: string, cache: BuildCache): string {
   }
 
   const selectors: string[] = [];
-  ast.stylesheet.rules.forEach((rule) => {
-    if ('selectors' in rule) {
-      (rule.selectors || []).forEach((selector: string) => {
+  const medias: string[] = [];
+  function getSelectors(rule: Rule | Media | NodeWithRules) {
+    if ('selectors' in rule && rule.selectors) {
+      rule.selectors.forEach((selector: string) => {
         if (HOVER_SELECTOR.test(selector)) {
           selectors.push(selector);
         }
       });
     }
-  });
-
-  if (selectors.length === 0) {
-    return cssText;
+    if ('media' in rule && rule.media && MEDIA_SELECTOR.test(rule.media)) {
+      medias.push(rule.media);
+    }
+    if ('rules' in rule && rule.rules) {
+      rule.rules.forEach(getSelectors);
+    }
   }
+  getSelectors(ast.stylesheet);
 
-  const selectorMatcher = new RegExp(
-    selectors
-      .filter((selector, index) => selectors.indexOf(selector) === index)
-      .sort((a, b) => b.length - a.length)
-      .map((selector) => {
-        return escapeRegExp(selector);
-      })
-      .join('|'),
-    'g',
-  );
-
-  const result = cssText.replace(selectorMatcher, (selector) => {
-    const newSelector = selector.replace(HOVER_SELECTOR_GLOBAL, '$1.\\:hover');
-    return `${selector}, ${newSelector}`;
-  });
+  let result = cssText;
+  if (selectors.length > 0) {
+    const selectorMatcher = new RegExp(
+      selectors
+        .filter((selector, index) => selectors.indexOf(selector) === index)
+        .sort((a, b) => b.length - a.length)
+        .map((selector) => {
+          return escapeRegExp(selector);
+        })
+        .join('|'),
+      'g',
+    );
+    result = result.replace(selectorMatcher, (selector) => {
+      const newSelector = selector.replace(
+        HOVER_SELECTOR_GLOBAL,
+        '$1.\\:hover',
+      );
+      return `${selector}, ${newSelector}`;
+    });
+  }
+  if (medias.length > 0) {
+    const mediaMatcher = new RegExp(
+      medias
+        .filter((media, index) => medias.indexOf(media) === index)
+        .sort((a, b) => b.length - a.length)
+        .map((media) => {
+          return escapeRegExp(media);
+        })
+        .join('|'),
+      'g',
+    );
+    result = result.replace(mediaMatcher, (media) => {
+      // not attempting to maintain min-device-width along with min-width
+      // (it's non standard)
+      return media.replace(MEDIA_SELECTOR_GLOBAL, '$1-$2');
+    });
+  }
   cache?.stylesWithHoverClass.set(cssText, result);
   return result;
 }
@@ -185,7 +213,7 @@ function buildNode(
         const isTextarea = tagName === 'textarea' && name === 'value';
         const isRemoteOrDynamicCss = tagName === 'style' && name === '_cssText';
         if (isRemoteOrDynamicCss && hackCss && typeof value === 'string') {
-          value = addHoverClass(value, cache);
+          value = adaptCssForReplay(value, cache);
         }
         if ((isTextarea || isRemoteOrDynamicCss) && typeof value === 'string') {
           const child = doc.createTextNode(value);
@@ -335,7 +363,7 @@ function buildNode(
     case NodeType.Text:
       return doc.createTextNode(
         n.isStyle && hackCss
-          ? addHoverClass(n.textContent, cache)
+          ? adaptCssForReplay(n.textContent, cache)
           : n.textContent,
       );
     case NodeType.CDATA:

packages/rrweb-snapshot/test/rebuild.test.ts

@@ -3,7 +3,11 @@
  */
 import * as fs from 'fs';
 import * as path from 'path';
-import { addHoverClass, buildNodeWithSN, createCache } from '../src/rebuild';
+import {
+  adaptCssForReplay,
+  buildNodeWithSN,
+  createCache,
+} from '../src/rebuild';
 import { NodeType } from '../src/types';
 import { createMirror, Mirror } from '../src/utils';
 
@@ -81,47 +85,90 @@ describe('rebuild', function () {
   describe('add hover class to hover selector related rules', function () {
     it('will do nothing to css text without :hover', () => {
       const cssText = 'body { color: white }';
-      expect(addHoverClass(cssText, cache)).toEqual(cssText);
+      expect(adaptCssForReplay(cssText, cache)).toEqual(cssText);
     });
 
     it('can add hover class to css text', () => {
       const cssText = '.a:hover { color: white }';
-      expect(addHoverClass(cssText, cache)).toEqual(
+      expect(adaptCssForReplay(cssText, cache)).toEqual(
         '.a:hover, .a.\\:hover { color: white }',
       );
     });
 
+    it('can correctly add hover when in middle of selector', () => {
+      const cssText = 'ul li a:hover img { color: white }';
+      expect(adaptCssForReplay(cssText, cache)).toEqual(
+        'ul li a:hover img, ul li a.\\:hover img { color: white }',
+      );
+    });
+
+    it('can correctly add hover on multiline selector', () => {
+      const cssText = `ul li.specified a:hover img,
+ul li.multiline
+b:hover
+img,
+ul li.specified c:hover img {
+  color: white
+}`;
+      expect(adaptCssForReplay(cssText, cache)).toEqual(
+        `ul li.specified a:hover img, ul li.specified a.\\:hover img,
+ul li.multiline
+b:hover
+img, ul li.multiline
+b.\\:hover
+img,
+ul li.specified c:hover img, ul li.specified c.\\:hover img {
+  color: white
+}`,
+      );
+    });
+
+    it('can add hover class within media query', () => {
+      const cssText = '@media screen { .m:hover { color: white } }';
+      expect(adaptCssForReplay(cssText, cache)).toEqual(
+        '@media screen { .m:hover, .m.\\:hover { color: white } }',
+      );
+    });
+
     it('can add hover class when there is multi selector', () => {
       const cssText = '.a, .b:hover, .c { color: white }';
-      expect(addHoverClass(cssText, cache)).toEqual(
+      expect(adaptCssForReplay(cssText, cache)).toEqual(
         '.a, .b:hover, .b.\\:hover, .c { color: white }',
       );
     });
 
     it('can add hover class when there is a multi selector with the same prefix', () => {
       const cssText = '.a:hover, .a:hover::after { color: white }';
-      expect(addHoverClass(cssText, cache)).toEqual(
+      expect(adaptCssForReplay(cssText, cache)).toEqual(
         '.a:hover, .a.\\:hover, .a:hover::after, .a.\\:hover::after { color: white }',
       );
     });
 
     it('can add hover class when :hover is not the end of selector', () => {
       const cssText = 'div:hover::after { color: white }';
-      expect(addHoverClass(cssText, cache)).toEqual(
+      expect(adaptCssForReplay(cssText, cache)).toEqual(
         'div:hover::after, div.\\:hover::after { color: white }',
       );
     });
 
     it('can add hover class when the selector has multi :hover', () => {
       const cssText = 'a:hover b:hover { color: white }';
-      expect(addHoverClass(cssText, cache)).toEqual(
+      expect(adaptCssForReplay(cssText, cache)).toEqual(
         'a:hover b:hover, a.\\:hover b.\\:hover { color: white }',
       );
     });
 
     it('will ignore :hover in css value', () => {
       const cssText = '.a::after { content: ":hover" }';
-      expect(addHoverClass(cssText, cache)).toEqual(cssText);
+      expect(adaptCssForReplay(cssText, cache)).toEqual(cssText);
+    });
+
+    it('can adapt media rules to replay context', () => {
+      const cssText =
+        '@media only screen and (min-device-width : 1200px) { .a { width: 10px; }}';
+      expect(adaptCssForReplay(cssText, cache)).toEqual(
+        '@media only screen and (min-width : 1200px) { .a { width: 10px; }}',
+      );
     });
 
     // this benchmark is unreliable when run in parallel with other tests
@@ -131,7 +178,7 @@ describe('rebuild', function () {
         'utf8',
       );
       const start = process.hrtime();
-      addHoverClass(cssText, cache);
+      adaptCssForReplay(cssText, cache);
       const end = process.hrtime(start);
       const duration = getDuration(end);
       expect(duration).toBeLessThan(100);
@@ -146,11 +193,11 @@ describe('rebuild', function () {
       );
 
       const start = process.hrtime();
-      addHoverClass(cssText, cache);
+      adaptCssForReplay(cssText, cache);
       const end = process.hrtime(start);
 
       const cachedStart = process.hrtime();
-      addHoverClass(cssText, cache);
+      adaptCssForReplay(cssText, cache);
       const cachedEnd = process.hrtime(cachedStart);
 
       expect(getDuration(cachedEnd) * factor).toBeLessThan(getDuration(end));