change theme for switching to darkmode!

Author: prashantpgit

theme.js

@@ -0,0 +1,33 @@
+const DARK_MODE = 'dark';
+const LIGHT_MODE = 'light';
+const THEME = 'mode';
+
+document.addEventListener(
+  'DOMContentLoaded', (event) => {
+    applyTheme();
+    const toggleSwitch = document.getElementById('toggle-switch');
+    toggleSwitch.onclick = function() {
+      let currentMode = localStorage.getItem(THEME);
+      localStorage.setItem(
+        THEME, 
+        currentMode === DARK_MODE ? LIGHT_MODE : DARK_MODE
+      );
+      applyTheme();
+    }
+  }
+);
+
+function applyTheme() {
+  let html = document.documentElement;
+  let currentMode = localStorage.getItem(THEME);
+  if (currentMode === DARK_MODE) {
+    html.classList.add(DARK_MODE);
+    document.getElementById('toggle-switch').innerHTML = 
+      '<i class="fas fa-sun fa-3x"></i>';
+  } 
+  else {
+    html.classList.remove(DARK_MODE);
+    document.getElementById('toggle-switch').innerHTML = 
+      '<i class="fas fa-moon fa-3x"></i>';
+  }
+}