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feat(website): Sync state changes across tabs #4174

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7ee181b
feat(website): Sync state changes across tabs
TheMythologist Aug 17, 2025
c81f680
Stick package versions
TheMythologist Aug 25, 2025
c800b86
Fix test issues after adding redux-state-sync
TheMythologist Aug 27, 2025
094c8b4
Mock redux-state-sync globally during jest
TheMythologist Aug 31, 2025
c5eba29
Resolve lint errors during jest mocking
TheMythologist Aug 31, 2025
61dc829
Merge branch 'master' into sync-across-tabs
zwliew Aug 31, 2025
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3 changes: 3 additions & 0 deletions website/package.json
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Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,7 @@
"@babel/preset-react": "7.26.3",
"@babel/preset-typescript": "7.26.0",
"@cfaester/enzyme-adapter-react-18": "0.8.0",
"@jest/globals": "29.7.0",
"@packtracker/webpack-plugin": "2.3.0",
"@pmmmwh/react-refresh-webpack-plugin": "0.5.15",
"@svgr/webpack": "8.1.0",
Expand All @@ -63,6 +64,7 @@
"@types/react-router-dom": "5.3.3",
"@types/react-scrollspy": "3.3.9",
"@types/redux-mock-store": "1.5.0",
"@types/redux-state-sync": "3.1.4",
"@types/use-subscription": "1.0.2",
"@types/webpack-env": "1.18.5",
"@typescript-eslint/eslint-plugin": "4.33.0",
Expand Down Expand Up @@ -168,6 +170,7 @@
"react-scrollspy": "3.4.3",
"redux": "4.2.1",
"redux-persist": "6.0.0",
"redux-state-sync": "3.1.4",
"redux-thunk": "2.4.2",
"reselect": "4.1.8",
"samlify": "2.7.7",
Expand Down
4 changes: 4 additions & 0 deletions website/scripts/test.js
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
import Adapter from '@cfaester/enzyme-adapter-react-18';
import { jest } from '@jest/globals';
import { configure } from 'enzyme';
import { setAutoFreeze } from 'immer';

Expand All @@ -15,3 +16,6 @@ configure({ adapter: new Adapter() });
// immer uses Object.freeze on returned state objects, which is incompatible with
// redux-persist. See https://github.com/rt2zz/redux-persist/issues/747
setAutoFreeze(false);

// Prevent causing errors during jest runs due to unclosed BroadcastChannel
jest.mock('redux-state-sync');
7 changes: 7 additions & 0 deletions website/src/__mocks__/redux-state-sync.ts
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Original file line number Diff line number Diff line change
@@ -0,0 +1,7 @@
import type { Middleware } from 'redux';

module.exports = {
createStateSyncMiddleware(): Middleware {
return () => (next) => (action) => next(action);
},
};
3 changes: 2 additions & 1 deletion website/src/bootstrapping/configure-store.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@ import { setAutoFreeze } from 'immer';
import rootReducer from 'reducers';
import requestsMiddleware from 'middlewares/requests-middleware';
import ravenMiddleware from 'middlewares/raven-middleware';
import stateSyncMiddleware from 'middlewares/state-sync-middleware';
import getLocalStorage from 'storage/localStorage';

import type { GetState } from 'types/redux';
Expand All @@ -25,7 +26,7 @@ export default function configureStore(defaultState?: State) {
// to reduce the amount of data NUSMods is using
getLocalStorage().removeItem('reduxState');

const middlewares = [ravenMiddleware, thunk, requestsMiddleware];
const middlewares = [ravenMiddleware, thunk, requestsMiddleware, stateSyncMiddleware];

if (NUSMODS_ENV === 'development') {
// eslint-disable-next-line @typescript-eslint/no-var-requires, global-require, import/no-extraneous-dependencies
Expand Down
31 changes: 31 additions & 0 deletions website/src/middlewares/state-sync-middleware.ts
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Original file line number Diff line number Diff line change
@@ -0,0 +1,31 @@
import type { AnyAction } from 'redux';
import { PERSIST, PURGE, REHYDRATE } from 'redux-persist';
import { createStateSyncMiddleware } from 'redux-state-sync';

const reduxStateSyncConfig = {
// Reference: https://github.com/aohua/redux-state-sync/issues/121#issuecomment-1770588046
// TL/DR: Channel name (which is set to a string in the default config) is auto-converted
// to the string "undefined" in the browser, but not in the test (jest) environment
channel: 'redux_state_sync',
predicate: (action: AnyAction) => {
// Reference: https://github.com/aohua/redux-state-sync/issues/53
const blacklist = [PERSIST, PURGE, REHYDRATE];

// redux-state-sync relies on BroadcastChannel, which only supports
// objects that are clonable by `structuredClone`
if (typeof action === 'function') {
return false;
}

// `FETCH_` request actions should not be synced to other tabs
if (action.type.toString().startsWith('FETCH_')) {
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@zwliew zwliew Sep 7, 2025 •
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hook.js:608 TypeError: Cannot read properties of undefined (reading 'find')
    at u (modules.ts:30:30)
    at d (modules.ts:35:16)
    at timetables.ts:168:21
    at mapValues.js:38:34
    at _createBaseFor.js:17:11
    at e.exports (_baseForOwn.js:13:20)
    at e.exports (mapValues.js:37:3)
    at ue (timetables.ts:167:10)
    at timetables.ts:127:14

The problem is that in getModuleSemesterData() of modules.ts, the semesterData field of module is undefined for a module that was synced over from another tab.

Perhaps a fix for this is to whitelist the FETCH_MODULE_REQUEST and FETCH_MODULE_SUCCESS actions, which are there to add module info (like semesterData) for newly added modules.

As an aside, I would be more comfortable with switching over to an action whitelist rather than a blacklist.

return false;
}

return !blacklist.includes(action.type);
},
};

const stateSyncMiddleware = createStateSyncMiddleware(reduxStateSyncConfig);

export default stateSyncMiddleware;
102 changes: 98 additions & 4 deletions website/yarn.lock
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Original file line number Diff line number Diff line change
Expand Up @@ -1090,6 +1090,11 @@
dependencies:
regenerator-runtime "^0.14.0"

"@babel/runtime@^7.6.2", "@babel/runtime@^7.7.2":
version "7.28.3"
resolved "https://registry.yarnpkg.com/@babel/runtime/-/runtime-7.28.3.tgz#75c5034b55ba868121668be5d5bb31cc64e6e61a"
integrity sha512-9uIQ10o0WGdpP6GDhXcdOJPJuDgFtIDtN/9+ArJQ2NAfAmiuhTQdzkaTGR33v43GYS2UrSA0eX2pPPHoFVvpxA==

"@babel/template@^7.25.9", "@babel/template@^7.3.3":
version "7.25.9"
resolved "https://registry.yarnpkg.com/@babel/template/-/template-7.25.9.tgz#ecb62d81a8a6f5dc5fe8abfc3901fc52ddf15016"
Expand Down Expand Up @@ -1269,7 +1274,7 @@
jest-mock "^29.7.0"
jest-util "^29.7.0"

"@jest/globals@^29.7.0":
"@jest/globals@29.7.0", "@jest/globals@^29.7.0":
version "29.7.0"
resolved "https://registry.yarnpkg.com/@jest/globals/-/globals-29.7.0.tgz#8d9290f9ec47ff772607fa864ca1d5a2efae1d4d"
integrity sha512-mpiz3dutLbkW2MNFubUGUEVLkTGiqW6yLVTA+JbP6fI6J5iL9Y0Nlg8k95pcF8ctKwCS7WVxteBs29hhfAotzQ==
Expand Down Expand Up @@ -2509,6 +2514,14 @@
dependencies:
redux "^4.0.5"

"@types/[email protected]":
version "3.1.4"
resolved "https://registry.yarnpkg.com/@types/redux-state-sync/-/redux-state-sync-3.1.4.tgz#907fab8c7a127673fcc2c4d505cd7facc0e48852"
integrity sha512-tJjipBwPJzmeKhpLHWsgfAG3yHR+QJB5Dp6e9TPyp8RTXH7GIL7yj09A76LdydUUXE1+Ev3afJF2NuN9qf1sPw==
dependencies:
broadcast-channel "^2.1.8"
redux "^4.0.1"

"@types/[email protected]":
version "0.12.2"
resolved "https://registry.yarnpkg.com/@types/retry/-/retry-0.12.2.tgz#ed279a64fa438bb69f2480eda44937912bb7480a"
Expand Down Expand Up @@ -3537,6 +3550,11 @@ bfj@^6.1.1:
hoopy "^0.1.4"
tryer "^1.0.1"

big-integer@^1.6.16:
version "1.6.52"
resolved "https://registry.yarnpkg.com/big-integer/-/big-integer-1.6.52.tgz#60a887f3047614a8e1bffe5d7173490a97dc8c85"
integrity sha512-QxD8cf2eVqJOOz63z6JIN9BzvVs/dlySa5HGSBH5xtR8dPteIRQnBxxKqkNTiT6jbDTF6jAfrd4oMcND9RGbQg==

big.js@^5.2.2:
version "5.2.2"
resolved "https://registry.yarnpkg.com/big.js/-/big.js-5.2.2.tgz#65f0af382f578bcdc742bd9c281e9cb2d7768328"
Expand Down Expand Up @@ -3629,6 +3647,33 @@ braces@^3.0.3, braces@~3.0.2:
dependencies:
fill-range "^7.1.1"

broadcast-channel@^2.1.8:
version "2.3.4"
resolved "https://registry.yarnpkg.com/broadcast-channel/-/broadcast-channel-2.3.4.tgz#cede8a9cded517c7273063582da71fa4f809ee2c"
integrity sha512-cx1/dSb6KZ9HW1VtlqM/HLPjrdyzkKoteVmUpLXEpra00mDQW/F9ieDkoavuZMoh9/hC/6OplGzCERsZBfz/Wg==
dependencies:
"@babel/runtime" "^7.6.2"
detect-node "^2.0.4"
js-sha3 "0.8.0"
microseconds "0.1.0"
nano-time "1.0.0"
rimraf "2.6.3"
unload "2.2.0"

broadcast-channel@^3.1.0:
version "3.7.0"
resolved "https://registry.yarnpkg.com/broadcast-channel/-/broadcast-channel-3.7.0.tgz#2dfa5c7b4289547ac3f6705f9c00af8723889937"
integrity sha512-cIAKJXAxGJceNZGTZSBzMxzyOn72cVgPnKx4dc6LRjQgbaJUQqhy5rzL3zbMxkMWsGKkv2hSFkPRMEXfoMZ2Mg==
dependencies:
"@babel/runtime" "^7.7.2"
detect-node "^2.1.0"
js-sha3 "0.8.0"
microseconds "0.2.0"
nano-time "1.0.0"
oblivious-set "1.0.0"
rimraf "3.0.2"
unload "2.2.0"

[email protected]:
version "1.3.0"
resolved "https://registry.yarnpkg.com/browser-stdout/-/browser-stdout-1.3.0.tgz#f351d32969d32fa5d7a5567154263d928ae3bd1f"
Expand Down Expand Up @@ -4828,7 +4873,7 @@ detect-newline@^3.0.0:
resolved "https://registry.yarnpkg.com/detect-newline/-/detect-newline-3.1.0.tgz#576f5dfc63ae1a192ff192d8ad3af6308991b651"
integrity sha512-TLz+x/vEXm/Y7P7wn1EJFNLxYpUD4TgMosxY6fAVJUnJMbupHBOncxyWUG9OpTaH9EBD7uFI5LfEgmMOc54DsA==

detect-node@^2.0.4:
detect-node@^2.0.4, detect-node@^2.1.0:
version "2.1.0"
resolved "https://registry.yarnpkg.com/detect-node/-/detect-node-2.1.0.tgz#c9c70775a49c3d03bc2c06d9a73be550f978f8b1"
integrity sha512-T0NIuQpnTvFDATNuHN5roPwSBG83rFsuO+MXXH9/3N1eFbn4wcPjttvjMLEPWJ0RGUYgQE7cGgS3tNxbqCGM7g==
Expand Down Expand Up @@ -8031,6 +8076,11 @@ jiti@^1.20.0:
resolved "https://registry.yarnpkg.com/jiti/-/jiti-1.21.6.tgz#6c7f7398dd4b3142767f9a168af2f317a428d268"
integrity sha512-2yTgeWTWzMWkHu6Jp9NKgePDaYHbntiwvYuuJLbbN9vl7DC9DvXKOB2BC3ZZ92D3cvV/aflH0osDfwpHepQ53w==

[email protected]:
version "0.8.0"
resolved "https://registry.yarnpkg.com/js-sha3/-/js-sha3-0.8.0.tgz#b9b7a5da73afad7dedd0f8c463954cbde6818840"
integrity sha512-gF1cRrHhIzNfToc802P800N8PpXS+evLLXfsVpowqmAFR9uwbi89WvXg2QspOmXL8QL86J4T1EpFu+yUkwJY3Q==

"js-tokens@^3.0.0 || ^4.0.0", js-tokens@^4.0.0:
version "4.0.0"
resolved "https://registry.yarnpkg.com/js-tokens/-/js-tokens-4.0.0.tgz#19203fb59991df98e3a287050d4647cdeaf32499"
Expand Down Expand Up @@ -8768,6 +8818,16 @@ micromatch@^4.0.2, micromatch@^4.0.4, micromatch@^4.0.5:
braces "^3.0.3"
picomatch "^2.3.1"

[email protected]:
version "0.1.0"
resolved "https://registry.yarnpkg.com/microseconds/-/microseconds-0.1.0.tgz#47dc7bcf62171b8030e2152fd82f12a6894a7119"
integrity sha512-yF2K4aHXKxO4OGhW7Ek2KLgKEAFbSblBLKlF6KzwQUhjK7+uAzatRr6fZ82bftdnuDQrkBHAJp5s8quj1ME3wA==

[email protected]:
version "0.2.0"
resolved "https://registry.yarnpkg.com/microseconds/-/microseconds-0.2.0.tgz#233b25f50c62a65d861f978a4a4f8ec18797dc39"
integrity sha512-n7DHHMjR1avBbSpsTBj6fmMGh2AGrifVV4e+WYc3Q9lO+xnSZ3NyhcBND3vzzatt05LFhoKFRxrIyklmLlUtyA==

[email protected]:
version "1.52.0"
resolved "https://registry.yarnpkg.com/mime-db/-/mime-db-1.52.0.tgz#bbabcdc02859f4987301c856e3387ce5ec43bf70"
Expand Down Expand Up @@ -8941,6 +9001,13 @@ multicast-dns@^7.2.5:
dns-packet "^5.2.2"
thunky "^1.0.2"

[email protected]:
version "1.0.0"
resolved "https://registry.yarnpkg.com/nano-time/-/nano-time-1.0.0.tgz#b0554f69ad89e22d0907f7a12b0993a5d96137ef"
integrity sha512-flnngywOoQ0lLQOTRNexn2gGSNuM9bKj9RZAWSzhQ+UJYaAFG9bac4DW9VHjUAzrOaIcajHybCTHe/bkvozQqA==
dependencies:
big-integer "^1.6.16"

nanoid@^3.3.7:
version "3.3.7"
resolved "https://registry.yarnpkg.com/nanoid/-/nanoid-3.3.7.tgz#d0c301a691bc8d54efa0a2226ccf3fe2fd656bd8"
Expand Down Expand Up @@ -9297,6 +9364,11 @@ object.values@^1.2.0, object.values@^1.2.1:
define-properties "^1.2.1"
es-object-atoms "^1.0.0"

[email protected]:
version "1.0.0"
resolved "https://registry.yarnpkg.com/oblivious-set/-/oblivious-set-1.0.0.tgz#c8316f2c2fb6ff7b11b6158db3234c49f733c566"
integrity sha512-z+pI07qxo4c2CulUHCDf9lcqDlMSo72N/4rLUpRXf6fu+q8vjt8y0xS+Tlf8NTJDdTXHbdeO1n3MlbctwEoXZw==

obuf@^1.0.0, obuf@^1.1.2:
version "1.1.2"
resolved "https://registry.yarnpkg.com/obuf/-/obuf-1.1.2.tgz#09bea3343d41859ebd446292d11c9d4db619084e"
Expand Down Expand Up @@ -10732,12 +10804,19 @@ [email protected]:
resolved "https://registry.yarnpkg.com/redux-persist/-/redux-persist-6.0.0.tgz#b4d2972f9859597c130d40d4b146fecdab51b3a8"
integrity sha512-71LLMbUq2r02ng2We9S215LtPu3fY0KgaGE0k8WRgl6RkqxtGfl7HUozz1Dftwsb0D/5mZ8dwAaPbtnzfvbEwQ==

[email protected]:
version "3.1.4"
resolved "https://registry.yarnpkg.com/redux-state-sync/-/redux-state-sync-3.1.4.tgz#b3a0a92a0c26d05b798c3e39e0ef215031a41323"
integrity sha512-nhJBzaXVXPXvUhQJ7m0LdoXBnrcw+cTYQ8bzW9DeJKdq6UNYynXwQWAlVUvsbT/hDV+vB6BC4DMLXkUVGpF2yQ==
dependencies:
broadcast-channel "^3.1.0"

[email protected]:
version "2.4.2"
resolved "https://registry.yarnpkg.com/redux-thunk/-/redux-thunk-2.4.2.tgz#b9d05d11994b99f7a91ea223e8b04cf0afa5ef3b"
integrity sha512-+P3TjtnP0k/FEjcBL5FZpoovtvrTNT/UXd4/sluaSyrURlSlhLSzEdfsTBW7WsKB6yPvgd7q/iZPICFjW4o57Q==

[email protected], redux@^4.0.0, redux@^4.0.4, redux@^4.0.5:
[email protected], redux@^4.0.0, redux@^4.0.1, redux@^4.0.4, redux@^4.0.5:
version "4.2.1"
resolved "https://registry.yarnpkg.com/redux/-/redux-4.2.1.tgz#c08f4306826c49b5e9dc901dee0452ea8fce6197"
integrity sha512-LAUYz4lc+Do8/g7aeRa8JkyDErK6ekstQaqWQrNRW//MY1TvCEpMtpTWvlQ+FPbWCx+Xixu/6SHt5N0HR+SB4w==
Expand Down Expand Up @@ -10993,7 +11072,14 @@ rgba-regex@^1.0.0:
resolved "https://registry.yarnpkg.com/rgba-regex/-/rgba-regex-1.0.0.tgz#43374e2e2ca0968b0ef1523460b7d730ff22eeb3"
integrity sha512-zgn5OjNQXLUTdq8m17KdaicF6w89TZs8ZU8y0AYENIU6wG8GG6LLm0yLSiPY8DmaYmHdgRW8rnApjoT0fQRfMg==

rimraf@^3.0.2:
[email protected]:
version "2.6.3"
resolved "https://registry.yarnpkg.com/rimraf/-/rimraf-2.6.3.tgz#b2d104fe0d8fb27cf9e0a1cda8262dd3833c6cab"
integrity sha512-mwqeW5XsA2qAejG46gYdENaxXjx9onRNCfn7L0duuP4hCuTIi/QO7PDK07KJfp1d+izWPrzEJDcSqBa0OZQriA==
dependencies:
glob "^7.1.3"

[email protected], rimraf@^3.0.2:
version "3.0.2"
resolved "https://registry.yarnpkg.com/rimraf/-/rimraf-3.0.2.tgz#f1a5402ba6220ad52cc1282bac1ae3aa49fd061a"
integrity sha512-JZkJMZkAGFFPP2YqXZXPbMlMBgsxzE8ILs4lMIX/2o0L9UBw9O/Y3o6wFw/i9YLapcUJWwqbi3kdxIPdC62TIA==
Expand Down Expand Up @@ -12595,6 +12681,14 @@ universalify@^2.0.0:
resolved "https://registry.yarnpkg.com/universalify/-/universalify-2.0.1.tgz#168efc2180964e6386d061e094df61afe239b18d"
integrity sha512-gptHNQghINnc/vTGIk0SOFGFNXw7JVrlRUtConJRlvaw6DuX0wO5Jeko9sWrMBhh+PsYAZ7oXAiOnf/UKogyiw==

[email protected]:
version "2.2.0"
resolved "https://registry.yarnpkg.com/unload/-/unload-2.2.0.tgz#ccc88fdcad345faa06a92039ec0f80b488880ef7"
integrity sha512-B60uB5TNBLtN6/LsgAf3udH9saB5p7gqJwcFfbOEZ8BcBHnGwCf6G/TGiEqkRAxX7zAFIUtzdrXQSdL3Q/wqNA==
dependencies:
"@babel/runtime" "^7.6.2"
detect-node "^2.0.4"

[email protected], unpipe@~1.0.0:
version "1.0.0"
resolved "https://registry.yarnpkg.com/unpipe/-/unpipe-1.0.0.tgz#b2bf4ee8514aae6165b4817829d21b2ef49904ec"
Expand Down