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fix: persist theme selection across reloads #49

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Merged
NagariaHussain merged 2 commits into from
Jul 20, 2026
Merged

fix: persist theme selection across reloads #49

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68fb272
feat: implement theme persistence with localStorage and add tests
ishad05 Jul 17, 2026
4866888
fix: update comment for theme persistence in index.html
ishad05 Jul 20, 2026
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7 changes: 7 additions & 0 deletions dashboard/index.html
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,13 @@
<link rel="icon" type="image/svg+xml" href="/assets/cs17_portal/dashboard/favicon.svg" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>CS17 Portal</title>
<!-- Apply the saved theme before the app bundle runs, so the page doesn't flash light before switching to dark on load. -->
<script>
try {
if (localStorage.getItem("theme") === "dark")
document.documentElement.classList.add("dark");
} catch (e) {}
</script>
Comment on lines +9 to +14

@NagariaHussain NagariaHussain Jul 17, 2026

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Doesn't app JS do it in JS side?

@ishad05 ishad05 Jul 20, 2026

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Yeah, but main.tsx executes just a bit late, and so screen flash is seen when switching to dark mode each time. In case of an inline script, the code executes at once, preventing that from happening. Will add a comment on index.html to explain this better.

<script type="module" src="/src/main.tsx"></script>
</head>
<body>
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22 changes: 2 additions & 20 deletions dashboard/src/faculty/FacultySettingsPage.tsx
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Expand Up @@ -9,29 +9,11 @@ import {
DialogFooter,
} from "@/components/ui/dialog";
import { Button } from "@/components/ui/button";

function getInitialTheme(): "light" | "dark" {
try {
const stored = localStorage.getItem("theme");
if (stored === "dark" || stored === "light") return stored;
} catch {}
return document.documentElement.classList.contains("dark") ? "dark" : "light";
}

function applyTheme(theme: "light" | "dark") {
if (theme === "dark") {
document.documentElement.classList.add("dark");
} else {
document.documentElement.classList.remove("dark");
}
try {
localStorage.setItem("theme", theme);
} catch {}
}
import { applyTheme, getStoredTheme, type Theme } from "@/lib/theme";

export default function FacultySettingsPage() {
const { profile } = useCurrentProfile();
const [theme, setTheme] = useState<"light" | "dark">(getInitialTheme);
const [theme, setTheme] = useState<Theme>(getStoredTheme);
const [showLogoutDialog, setShowLogoutDialog] = useState(false);

function toggleTheme() {
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20 changes: 20 additions & 0 deletions dashboard/src/lib/theme.ts
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@@ -0,0 +1,20 @@
export type Theme = "light" | "dark";

export function getStoredTheme(): Theme {
try {
const stored = localStorage.getItem("theme");
if (stored === "dark" || stored === "light") return stored;
} catch {}
return document.documentElement.classList.contains("dark") ? "dark" : "light";
}

export function applyTheme(theme: Theme): void {
setThemeClass(theme);
try {
localStorage.setItem("theme", theme);
} catch {}
}

function setThemeClass(theme: Theme): void {
document.documentElement.classList.toggle("dark", theme === "dark");
}
22 changes: 2 additions & 20 deletions dashboard/src/pages/SettingsPage.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -9,29 +9,11 @@ import {
DialogFooter,
} from "@/components/ui/dialog";
import { Button } from "@/components/ui/button";

function getInitialTheme(): "light" | "dark" {
try {
const stored = localStorage.getItem("theme");
if (stored === "dark" || stored === "light") return stored;
} catch {}
return document.documentElement.classList.contains("dark") ? "dark" : "light";
}

function applyTheme(theme: "light" | "dark") {
if (theme === "dark") {
document.documentElement.classList.add("dark");
} else {
document.documentElement.classList.remove("dark");
}
try {
localStorage.setItem("theme", theme);
} catch {}
}
import { applyTheme, getStoredTheme, type Theme } from "@/lib/theme";

export default function SettingsPage() {
const { student } = useCurrentStudent();
const [theme, setTheme] = useState<"light" | "dark">(getInitialTheme);
const [theme, setTheme] = useState<Theme>(getStoredTheme);
const [showLogoutDialog, setShowLogoutDialog] = useState(false);

function toggleTheme() {
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38 changes: 38 additions & 0 deletions e2e/tests/student-theme.spec.ts
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@@ -0,0 +1,38 @@
import { test, expect } from "@playwright/test";

test.describe("Theme persistence", () => {
test("keeps dark mode across a refresh and on other pages", async ({ page }) => {
await page.goto("/dashboard/settings");
await page.getByRole("switch").click();
await expect(page.locator("html")).toHaveClass(/dark/);

await page.reload();
await expect(page.locator("html")).toHaveClass(/dark/);
await expect(page.getByRole("switch")).toHaveAttribute("aria-checked", "true");

await page.goto("/dashboard/projects");
await expect(page.locator("html")).toHaveClass(/dark/);

await page.goto("/dashboard/settings");
await page.getByRole("switch").click();
await page.reload();
await expect(page.locator("html")).not.toHaveClass(/dark/);
});

test("applies dark before the app bundle runs, so there is no flash", async ({
page,
}) => {
await page.goto("/dashboard/settings");
await page.getByRole("switch").click();
await expect(page.locator("html")).toHaveClass(/dark/);

await page.route("**/dashboard/assets/*.js", async (route) => {
await new Promise((resolve) => setTimeout(resolve, 2000));
await route.continue();
});

await page.goto("/dashboard/projects", { waitUntil: "commit" });
await expect(page.locator("html")).toHaveClass(/dark/, { timeout: 1000 });
await expect(page.locator("#root")).toBeEmpty();
});
});
2 changes: 1 addition & 1 deletion playwright.config.ts
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Expand Up @@ -4,7 +4,7 @@ import path from "path";
const authFile = path.join(__dirname, "e2e", ".auth", "user.json");
const studentAuthFile = path.join(__dirname, "e2e", ".auth", "student.json");
const facultyAuthFile = path.join(__dirname, "e2e", ".auth", "faculty.json");
const studentSpecs = /student-submission\.spec\.ts/;
const studentSpecs = /(student-submission|student-theme)\.spec\.ts/;
const facultySpecs = /faculty-assignments-ui\.spec\.ts/;

const SITE_HOST = process.env.SITE_HOST || "cs17.portal:8000";
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