feat: remove lz compression (#654)

We've wanted to remove LZ compression for c2 years. #155

it is 5%+ of the bundle size.

Let's remove it

compression options are provided by decide, decide returns a harcoded list, and the library prefers gzip if it is present. So this can only negatively affect people using very, very old self-hosted versions and the latest pothog-js. And even then it would mean they would switch from lz64 to base64 so things would carry on working.

.gitignore

@@ -26,4 +26,5 @@ coverage
 react/dist
 test-result.json
 yarn-error.log
-/.eslintcache
+stats.html
+.eslintcache

cypress/e2e/capture.cy.js

@@ -1,14 +1,14 @@
 /// <reference types="cypress" />
 import { version } from '../../package.json'
 
-import { getBase64EncodedPayload, getGzipEncodedPayload, getLZStringEncodedPayload } from '../support/compression'
+import { getBase64EncodedPayload, getGzipEncodedPayload } from '../support/compression'
 
 const urlWithVersion = new RegExp(`&ver=${version}`)
 
 describe('Event capture', () => {
     given('options', () => ({}))
     given('sessionRecording', () => false)
-    given('supportedCompression', () => ['gzip', 'lz64'])
+    given('supportedCompression', () => ['gzip-js'])
 
     // :TRICKY: Use a custom start command over beforeEach to deal with given2 not being ready yet.
     const start = ({ waitForDecide = true } = {}) => {
@@ -332,47 +332,7 @@ describe('Event capture', () => {
     })
 
     describe('decoding the payload', () => {
-        it('contains the correct headers and payload after an event', () => {
-            start()
-
-            // Pageview will be sent immediately
-            cy.wait('@capture').should(({ request, url }) => {
-                expect(request.headers).to.eql({
-                    'Content-Type': 'application/x-www-form-urlencoded',
-                })
-
-                expect(url).to.match(urlWithVersion)
-                const captures = getBase64EncodedPayload(request)
-
-                expect(captures['event']).to.equal('$pageview')
-            })
-
-            cy.get('[data-cy-custom-event-button]').click()
-            cy.get('[data-cy-custom-event-button]').click()
-            cy.phCaptures().should('have.length', 5)
-            cy.phCaptures().should('include', '$autocapture')
-            cy.phCaptures().should('include', 'custom-event')
-
-            cy.wait('@capture').should(({ request, url }) => {
-                expect(request.headers).to.eql({
-                    'Content-Type': 'application/x-www-form-urlencoded',
-                })
-
-                expect(url).to.match(urlWithVersion)
-                const captures = getLZStringEncodedPayload(request)
-
-                expect(captures.map(({ event }) => event)).to.deep.equal([
-                    '$autocapture',
-                    'custom-event',
-                    '$autocapture',
-                    'custom-event',
-                ])
-            })
-        })
-
         describe('gzip-js supported', () => {
-            given('supportedCompression', () => ['gzip-js'])
-
             it('contains the correct payload after an event', () => {
                 start()
                 // Pageview will be sent immediately

cypress/support/compression.js

@@ -1,16 +1,10 @@
 import * as fflate from 'fflate'
-import { LZString } from '../../src/lz-string'
 
 export function getBase64EncodedPayload(request) {
     const data = decodeURIComponent(request.body.match(/data=(.*)/)[1])
     return JSON.parse(Buffer.from(data, 'base64'))
 }
 
-export function getLZStringEncodedPayload(request) {
-    const data = decodeURIComponent(request.body.match(/data=(.*)&compression=lz64/)[1])
-    return JSON.parse(LZString.decompressFromBase64(data))
-}
-
 export async function getGzipEncodedPayload(requestBody) {
     const data = new Uint8Array(await requestBody.arrayBuffer())
     const decoded = fflate.strFromU8(fflate.decompressSync(data))

package.json

@@ -82,6 +82,7 @@
         "prettier": "^2.7.1",
         "rollup": "^2.77.0",
         "rollup-plugin-dts": "^4.2.2",
+        "rollup-plugin-visualizer": "^5.9.0",
         "rrweb": "^1.1.3",
         "rrweb2": "npm:[email protected]",
         "sinon": "9.0.2",

rollup.config.js

@@ -5,6 +5,7 @@ import typescript from '@rollup/plugin-typescript'
 import dts from 'rollup-plugin-dts'
 import pkg from './package.json'
 import terser from '@rollup/plugin-terser'
+import { visualizer } from 'rollup-plugin-visualizer'
 
 const extensions = ['.js', '.jsx', '.ts', '.tsx']
 const plugins = [
@@ -17,6 +18,7 @@ const plugins = [
         presets: ['@babel/preset-env'],
     }),
     terser({ toplevel: true }),
+    visualizer(),
 ]
 
 export default [

src/__tests__/__snapshots__/compression.js.snap

@@ -73,15 +73,3 @@ Array [
   },
 ]
 `;
-
-exports[`compressData() handles lz64 1`] = `
-Array [
-  Object {
-    "compression": "lz64",
-    "data": "N4IgNghgTg5gpgfQNZwJ4gFwggIwMa4H6EnFlEWmXlW033WN1MPNusctfvec/99BvYQJFDRE8VLEzJs6XMULl81UrUr1WzTo17t+3QeNHTh8yYtnLN63asPbj+09cv3zz8xABfIA",
-  },
-  Object {
-    "method": "POST",
-  },
-]
-`;

src/__tests__/compression.js

@@ -13,15 +13,18 @@ describe('decideCompression()', () => {
     })
 
     it('returns gzip-js if all compressions supported', () => {
-        given('compressionSupport', () => ({ lz64: true, 'gzip-js': true }))
+        given('compressionSupport', () => ({
+            'gzip-js': true,
+            'a different thing that is either deprecated or new': true,
+        }))
 
         expect(given.subject).toEqual('gzip-js')
     })
 
-    it('returns lz64 if supported', () => {
-        given('compressionSupport', () => ({ lz64: true, 'gzip-js': false }))
+    it('returns base64 if only unexpected compression is received', () => {
+        given('compressionSupport', () => ({ 'the new compression that is not supported yet': true }))
 
-        expect(given.subject).toEqual('lz64')
+        expect(given.subject).toEqual('base64')
     })
 })
 
@@ -37,12 +40,6 @@ describe('compressData()', () => {
         expect(given.subject).toMatchSnapshot()
     })
 
-    it('handles lz64', () => {
-        given('compression', () => 'lz64')
-
-        expect(given.subject).toMatchSnapshot()
-    })
-
     it('handles gzip-js', () => {
         given('compression', () => 'gzip-js')
 
@@ -67,7 +64,7 @@ describe('Payload Compression', () => {
                 _prepare_callback: sandbox.spy((callback) => callback),
                 _send_request: sandbox.spy((url, params, options, callback) => {
                     if (url === 'https://test.com/decide/?v=3') {
-                        callback({ config: { enable_collect_everything: true }, supportedCompression: ['lz64'] })
+                        callback({ config: { enable_collect_everything: true }, supportedCompression: ['gzip-js'] })
                     } else {
                         throw new Error('Should not get here')
                     }
@@ -112,7 +109,7 @@ describe('Payload Compression', () => {
         it('should save supported compression in instance', () => {
             new Decide(lib).call()
             autocapture.init(lib)
-            expect(lib.compression).toEqual({ lz64: true })
+            expect(lib.compression).toEqual({ 'gzip-js': true })
         })
     })
 })

src/compression.ts

@@ -1,13 +1,10 @@
-import { LZString } from './lz-string'
 import { gzipSync, strToU8 } from 'fflate'
 import { _base64Encode } from './utils'
 import { Compression, CompressionData, XHROptions } from './types'
 
 export function decideCompression(compressionSupport: Partial<Record<Compression, boolean>>): Compression {
     if (compressionSupport[Compression.GZipJS]) {
         return Compression.GZipJS
-    } else if (compressionSupport[Compression.LZ64]) {
-        return Compression.LZ64
     } else {
         return Compression.Base64
     }
@@ -18,9 +15,7 @@ export function compressData(
     jsonData: string,
     options: XHROptions
 ): [CompressionData | Uint8Array, XHROptions] {
-    if (compression === Compression.LZ64) {
-        return [{ data: LZString.compressToBase64(jsonData), compression: Compression.LZ64 }, options]
-    } else if (compression === Compression.GZipJS) {
+    if (compression === Compression.GZipJS) {
         // :TRICKY: This returns an UInt8Array. We don't encode this to a string - returning a blob will do this for us.
         return [
             gzipSync(strToU8(jsonData), { mtime: 0 }),