feat: add option to set default theme and hide toggle button (#146)

resolves #135 

Light / dark theme can be configured via:

```yaml
  theme:
    # light | dark | system
    default: system
    displayToggle: true
```

assets/js/theme.js

@@ -1,40 +1,51 @@
-// Dark theme toggle
+// Light / Dark theme toggle
+(function () {
+  const defaultTheme = '{{ site.Params.theme.default | default `system`}}'
 
-const themeToggleButtons = document.querySelectorAll(".theme-toggle");
+  const themeToggleButtons = document.querySelectorAll(".theme-toggle");
 
-// Change the icons inside the button based on previous settings
-if (
+  // Change the icons of the buttons based on previous settings or system theme
+  if (
     localStorage.getItem("color-theme") === "dark" ||
-  (!("color-theme" in localStorage) && window.matchMedia("(prefers-color-scheme: dark)").matches)
-) {
+    (!("color-theme" in localStorage) &&
+      ((window.matchMedia("(prefers-color-scheme: dark)").matches && defaultTheme === "system") || defaultTheme === "dark"))
+  ) {
     themeToggleButtons.forEach((el) => el.dataset.theme = "dark");
-} else {
+  } else {
     themeToggleButtons.forEach((el) => el.dataset.theme = "light");
-}
+  }
 
-themeToggleButtons.forEach((el) => {
+  // Add click event handler to the buttons
+  themeToggleButtons.forEach((el) => {
     el.addEventListener("click", function () {
       if (localStorage.getItem("color-theme")) {
         if (localStorage.getItem("color-theme") === "light") {
-        document.documentElement.classList.add("dark");
-        document.documentElement.style.colorScheme = "dark";
+          setDarkTheme();
           localStorage.setItem("color-theme", "dark");
         } else {
-        document.documentElement.classList.remove("dark");
-        document.documentElement.style.colorScheme = "light";
+          setLightTheme();
           localStorage.setItem("color-theme", "light");
         }
       } else {
         if (document.documentElement.classList.contains("dark")) {
-        document.documentElement.classList.remove("dark");
-        document.documentElement.style.colorScheme = "light";
+          setLightTheme();
           localStorage.setItem("color-theme", "light");
         } else {
-        document.documentElement.classList.add("dark");
-        document.documentElement.style.colorScheme = "dark";
+          setDarkTheme();
           localStorage.setItem("color-theme", "dark");
         }
       }
       el.dataset.theme = document.documentElement.classList.contains("dark") ? "dark" : "light";
     });
-});
+  });
+
+  // Listen for system theme changes
+  window.matchMedia("(prefers-color-scheme: dark)").addEventListener("change", (e) => {
+    if (defaultTheme === "system" && !("color-theme" in localStorage)) {
+      e.matches ? setDarkTheme() : setLightTheme();
+      themeToggleButtons.forEach((el) =>
+        el.dataset.theme = document.documentElement.classList.contains("dark") ? "dark" : "light"
+      );
+    }
+  });
+})();

exampleSite/content/docs/guide/configuration.md

@@ -5,7 +5,7 @@ weight: 2
 
 Hugo reads its configuration from `hugo.yaml` in the root of your Hugo site.
 The config file is where you can configure all aspects of your site.
-You can find the config file for this site in `exampleSite/hugo.yaml` as a good starting point.
+Check out the config file for this site [`exampleSite/hugo.yaml`](https://github.com/imfing/hextra/blob/main/exampleSite/hugo.yaml) on GitHub to get a comprehensive idea of available settings and best practices.
 
 <!--more-->
 
@@ -181,6 +181,26 @@ Include both `favicon.ico` and `favicon.svg` files in your project to ensure you
 While `favicon.ico` is generally for older browsers, `favicon.svg` is supported by modern ones. The optional `favicon-dark.svg` can be included for a tailored experience in dark mode.
 Feel free to use tools like [favicon.io](https://favicon.io/) or [favycon](https://github.com/ruisaraiva19/favycon) to generate these icons.
 
+### Theme Configuration
+
+Use the `theme` setting to configure the default theme mode and toggle button, allowing visitors to switch between light or dark mode.
+
+```yaml {filename="hugo.yaml"}
+params:
+  theme:
+    # light | dark | system
+    default: system
+    displayToggle: true
+```
+
+Options for `theme.default`:
+
+- `light` - always use light mode
+- `dark` - always use dark mode
+- `system` - sync with the operating system setting (default)
+
+The `theme.displayToggle` parameter allows you to display a toggle button for changing themes.
+When set to `true`, visitors can switch between light or dark mode, overriding the default setting.
 
 ### Page Width
 
@@ -193,8 +213,7 @@ params:
     width: wide
 ```
 
-There are three available options: `full`, `wide`, and `normal`.
-By default, the page width is set to `normal`.
+There are three available options: `full`, `wide`, and `normal`. By default, the page width is set to `normal`.
 
 Similarly, the width of the navbar and footer can be customized by the `params.navbar.width` and `params.footer.width` parameters.
 
@@ -215,7 +234,8 @@ params:
       index: content
 ```
 
-available options for `flexsearch.index`:
+Options for `flexsearch.index`:
+
 - `content` - full content of the page (default)
 - `summary` - summary of the page, see [Hugo Content Summaries](https://gohugo.io/content-management/summaries/) for more details
 - `heading` - level 1 and level 2 headings

exampleSite/hugo.yaml

@@ -109,6 +109,11 @@ params:
     # full (100%), wide (90rem), normal (1280px)
     width: normal
 
+  theme:
+    # light | dark | system
+    default: system
+    displayToggle: true
+
   footer:
     displayCopyright: true
     displayPoweredBy: true

layouts/partials/footer.html

@@ -1,4 +1,5 @@
 {{- $enableFooterSwitches := .Scratch.Get "enableFooterSwitches" | default false -}}
+{{- $displayThemeToggle := site.Params.theme.displayToggle | default true -}}
 
 {{- $copyright := (T "copyright") | default "© 2023 Hextra." -}}
 
@@ -11,16 +12,19 @@
   {{ end -}}
 {{- end -}}
 
+
 <footer class="hextra-footer bg-gray-100 pb-[env(safe-area-inset-bottom)] dark:bg-neutral-900 print:bg-transparent">
-  {{- if $enableFooterSwitches }}
-    <div class='mx-auto flex gap-2 py-2 px-4 {{ $footerWidth }}'>
+  {{- if $enableFooterSwitches -}}
+    <div class="mx-auto flex gap-2 py-2 px-4 {{ $footerWidth }}">
       {{- partial "language-switch.html" (dict "context" .) -}}
-      {{- partial "theme-toggle.html" -}}
+      {{- with $displayThemeToggle }}{{ partial "theme-toggle.html" }}{{ end -}}
     </div>
-  {{ end -}}
+    {{- if or site.IsMultiLingual $displayThemeToggle -}}
       <hr class="dark:border-neutral-800" />
+    {{- end -}}
+  {{- end -}}
   <div
-    class='{{ $footerWidth }} mx-auto flex justify-center py-12 pl-[max(env(safe-area-inset-left),1.5rem)] pr-[max(env(safe-area-inset-right),1.5rem)] text-gray-600 dark:text-gray-400 md:justify-start'
+    class="{{ $footerWidth }} mx-auto flex justify-center py-12 pl-[max(env(safe-area-inset-left),1.5rem)] pr-[max(env(safe-area-inset-right),1.5rem)] text-gray-600 dark:text-gray-400 md:justify-start"
   >
     <div class="flex w-full flex-col items-center sm:items-start">
       {{- if (.Site.Params.footer.displayPoweredBy | default true) }}<div class="font-semibold">{{ template "theme-credit" . }}</div>{{ end }}

layouts/partials/head.html

@@ -33,13 +33,25 @@
 
   <script>
     /* Initialize light/dark mode */
-    if (localStorage.getItem("color-theme") === "dark" || (!("color-theme" in localStorage) && window.matchMedia("(prefers-color-scheme: dark)").matches)) {
+    const defaultTheme = '{{ site.Params.theme.default | default `system`}}';
+
+    const setDarkTheme = () => {
       document.documentElement.classList.add("dark");
       document.documentElement.style.colorScheme = "dark";
-    } else {
+    }
+    const setLightTheme = () => {
       document.documentElement.classList.remove("dark");
       document.documentElement.style.colorScheme = "light";
     }
+
+    if ("color-theme" in localStorage) {
+      localStorage.getItem("color-theme") === "dark" ? setDarkTheme() : setLightTheme();
+    } else {
+      defaultTheme === "dark" ? setDarkTheme() : setLightTheme();
+      if (defaultTheme === "system") {
+        window.matchMedia("(prefers-color-scheme: dark)").matches ? setDarkTheme() : setLightTheme();
+      }
+    }
   </script>
 
   {{ partial "custom/head-end.html" . }}

layouts/partials/scripts.html

@@ -1,4 +1,4 @@
-{{- $jsTheme := resources.Get "js/theme.js" -}}
+{{- $jsTheme := resources.Get "js/theme.js" | resources.ExecuteAsTemplate "theme.js" . -}}
 {{- $jsMenu := resources.Get "js/menu.js" -}}
 {{- $jsTabs := resources.Get "js/tabs.js" -}}
 {{- $jsLang := resources.Get "js/lang.js" -}}

layouts/partials/sidebar.html

@@ -34,17 +34,21 @@
     {{ end -}}
   </div>
   {{/* Hide theme switch when sidebar is disabled */}}
-  {{ $switchesClass := cond $disableSidebar "md:hidden" "" }}
+  {{ $switchesClass := cond $disableSidebar "md:hidden" "" -}}
+  {{ $displayThemeToggle := (site.Params.theme.displayToggle | default true) -}}
+
+  {{ if or site.IsMultiLingual $displayThemeToggle }}
     <div class="{{ $switchesClass }} {{ with site.IsMultiLingual }}justify-end{{ end }} sticky bottom-0 bg-white dark:bg-dark mx-4 py-4 shadow-[0_-12px_16px_#fff] flex items-center gap-2 dark:border-neutral-800 dark:shadow-[0_-12px_16px_#111] contrast-more:border-neutral-400 contrast-more:shadow-none contrast-more:dark:shadow-none border-t" data-toggle-animation="show">
-    {{- with site.IsMultiLingual }}
-      {{ partial "language-switch" (dict "context" $context "grow" true) }}
-      {{ partial "theme-toggle" (dict "hideLabel" true) }}
-    {{ else }}
-      <div class="flex grow flex-col">
-        {{ partial "theme-toggle" }}
-      </div>
-    {{ end -}}
+      {{- with site.IsMultiLingual -}}
+        {{- partial "language-switch" (dict "context" $context "grow" true) -}}
+        {{- with $displayThemeToggle }}{{ partial "theme-toggle" (dict "hideLabel" true) }}{{ end -}}
+      {{- else -}}
+        {{- with $displayThemeToggle -}}
+          <div class="flex grow flex-col">{{ partial "theme-toggle" }}</div>
+        {{- end -}}
+      {{- end -}}
     </div>
+  {{- end -}}
 </aside>
 
 {{- define "sidebar-main" -}}