Allow blocking elements by selector (#50)

* Extract method (isElementBlocked) and add tests

* Add blockSelector argument to snapshot

If blockSelector is passed, it will be matched against the element.

Reasoning: Mutating class names can get messy, so providing another hook
helps keep code clean by using data-attributes instead.

package.json

@@ -34,12 +34,14 @@
   "homepage": "https://github.com/rrweb-io/rrweb-snapshot#readme",
   "devDependencies": {
     "@types/chai": "^4.1.4",
+    "@types/jsdom": "^16.2.4",
     "@types/mocha": "^5.2.5",
     "@types/node": "^10.11.3",
     "@types/puppeteer": "^1.12.4",
     "chai": "^4.1.2",
     "cross-env": "^5.2.0",
     "jest-snapshot": "^23.6.0",
+    "jsdom": "^16.4.0",
     "mocha": "^5.2.0",
     "puppeteer": "^1.15.0",
     "rollup": "^0.66.4",

src/snapshot.ts

@@ -162,10 +162,34 @@ export function transformAttribute(
   }
 }
 
+export function _isBlockedElement(
+  element: HTMLElement,
+  blockClass: string | RegExp,
+  blockSelector: string | null,
+): boolean {
+  if (typeof blockClass === 'string') {
+    if (element.classList.contains(blockClass)) {
+      return true;
+    }
+  } else {
+    element.classList.forEach((className) => {
+      if (blockClass.test(className)) {
+        return true;
+      }
+    });
+  }
+  if (blockSelector) {
+    return element.matches(blockSelector)
+  }
+
+  return false;
+}
+
 function serializeNode(
   n: Node,
   doc: Document,
   blockClass: string | RegExp,
+  blockSelector: string | null,
   inlineStylesheet: boolean,
   maskInputOptions: MaskInputOptions = {},
   recordCanvas: boolean,
@@ -184,16 +208,7 @@ function serializeNode(
         systemId: (n as DocumentType).systemId,
       };
     case n.ELEMENT_NODE:
-      let needBlock = false;
-      if (typeof blockClass === 'string') {
-        needBlock = (n as HTMLElement).classList.contains(blockClass);
-      } else {
-        (n as HTMLElement).classList.forEach((className) => {
-          if (blockClass.test(className)) {
-            needBlock = true;
-          }
-        });
-      }
+      const needBlock = _isBlockedElement(n as HTMLElement, blockClass, blockSelector);
       const tagName = getValidTagName((n as HTMLElement).tagName);
       let attributes: attributes = {};
       for (const { name, value } of Array.from((n as HTMLElement).attributes)) {
@@ -406,6 +421,7 @@ export function serializeNodeWithId(
   doc: Document,
   map: idNodeMap,
   blockClass: string | RegExp,
+  blockSelector: string | null,
   skipChild = false,
   inlineStylesheet = true,
   maskInputOptions?: MaskInputOptions,
@@ -417,6 +433,7 @@ export function serializeNodeWithId(
     n,
     doc,
     blockClass,
+    blockSelector,
     inlineStylesheet,
     maskInputOptions,
     recordCanvas || false,
@@ -472,6 +489,7 @@ export function serializeNodeWithId(
         doc,
         map,
         blockClass,
+        blockSelector,
         skipChild,
         inlineStylesheet,
         maskInputOptions,
@@ -494,6 +512,7 @@ function snapshot(
   maskAllInputsOrOptions: boolean | MaskInputOptions,
   slimDOMSensibleOrOptions: boolean | SlimDOMOptions,
   recordCanvas?: boolean,
+  blockSelector: string | null = null,
 ): [serializedNodeWithId | null, idNodeMap] {
   const idNodeMap: idNodeMap = {};
   const maskInputOptions: MaskInputOptions =
@@ -543,6 +562,7 @@ function snapshot(
       n,
       idNodeMap,
       blockClass,
+      blockSelector,
       false,
       inlineStylesheet,
       maskInputOptions,

test/snapshot.test.ts

@@ -1,6 +1,7 @@
 import 'mocha';
+import { JSDOM } from 'jsdom';
 import { expect } from 'chai';
-import { absoluteToStylesheet } from '../src/snapshot';
+import { absoluteToStylesheet, _isBlockedElement } from '../src/snapshot';
 
 describe('absolute url to stylesheet', () => {
   const href = 'http://localhost/css/style.css';
@@ -83,3 +84,27 @@ describe('absolute url to stylesheet', () => {
     expect(absoluteToStylesheet(`url('')`, href)).to.equal(`url('')`);
   });
 });
+
+describe('isBlockedElement()', () => {
+  const subject = (html: string, opt: any = {}) =>
+    _isBlockedElement(render(html), 'rr-block', opt.blockSelector)
+
+  const render = (html: string): HTMLElement =>
+    JSDOM.fragment(html).querySelector('div')!
+
+  it('can handle empty elements', () => {
+    expect(subject('<div />')).to.equal(false)
+  })
+
+  it('blocks prohibited className', () => {
+    expect(subject('<div class="foo rr-block bar" />')).to.equal(true)
+  })
+
+  it('does not block random data selector', () => {
+    expect(subject('<div data-rr-block />')).to.equal(false)
+  })
+
+  it('blocks blocked selector', () => {
+    expect(subject('<div data-rr-block />', { blockSelector: '[data-rr-block]' })).to.equal(true)
+  })
+})

typings/snapshot.d.ts

@@ -3,8 +3,9 @@ export declare const IGNORED_NODE = -2;
 export declare function absoluteToStylesheet(cssText: string | null, href: string): string;
 export declare function absoluteToDoc(doc: Document, attributeValue: string): string;
 export declare function transformAttribute(doc: Document, name: string, value: string): string;
-export declare function serializeNodeWithId(n: Node | INode, doc: Document, map: idNodeMap, blockClass: string | RegExp, skipChild?: boolean, inlineStylesheet?: boolean, maskInputOptions?: MaskInputOptions, slimDOMOptions?: SlimDOMOptions, recordCanvas?: boolean, preserveWhiteSpace?: boolean): serializedNodeWithId | null;
-declare function snapshot(n: Document, blockClass: string | RegExp | undefined, inlineStylesheet: boolean | undefined, maskAllInputsOrOptions: boolean | MaskInputOptions, slimDOMSensibleOrOptions: boolean | SlimDOMOptions, recordCanvas?: boolean): [serializedNodeWithId | null, idNodeMap];
+export declare function _isBlockedElement(element: HTMLElement, blockClass: string | RegExp, blockSelector: string | null): boolean;
+export declare function serializeNodeWithId(n: Node | INode, doc: Document, map: idNodeMap, blockClass: string | RegExp, blockSelector: string | null, skipChild?: boolean, inlineStylesheet?: boolean, maskInputOptions?: MaskInputOptions, slimDOMOptions?: SlimDOMOptions, recordCanvas?: boolean, preserveWhiteSpace?: boolean): serializedNodeWithId | null;
+declare function snapshot(n: Document, blockClass: string | RegExp | undefined, inlineStylesheet: boolean | undefined, maskAllInputsOrOptions: boolean | MaskInputOptions, slimDOMSensibleOrOptions: boolean | SlimDOMOptions, recordCanvas?: boolean, blockSelector?: string | null): [serializedNodeWithId | null, idNodeMap];
 export declare function visitSnapshot(node: serializedNodeWithId, onVisit: (node: serializedNodeWithId) => unknown): void;
 export declare function cleanupSnapshot(): void;
 export default snapshot;