Implemented theme switcher (light/dark)

scripts/main.js

@@ -0,0 +1,49 @@
+const theme_switcher = document.getElementById("theme-switcher");
+const imgs = document.getElementsByTagName("img");
+
+let theme = window.localStorage.getItem("theme");
+
+if (theme !== null) {
+  if (theme === "light") {
+    changeToLightTheme();
+  } else {
+    changeToDarkTheme();
+  }
+} else {
+  if (
+    window.matchMedia &&
+    window.matchMedia("(prefers-color-scheme: dark)").matches
+  ) {
+    changeToDarkTheme();
+  }
+}
+
+theme_switcher.addEventListener("click", () => {
+  if (theme_switcher.textContent.indexOf("off") !== -1) {
+    changeToDarkTheme();
+  } else {
+    changeToLightTheme();
+  }
+});
+
+function changeToDarkTheme() {
+  theme_switcher.textContent = "turn the light on";
+  document.documentElement.style.setProperty("--border", "var(--dark-border)");
+  document.documentElement.style.setProperty("--text", "var(--dark-text)");
+  document.documentElement.style.setProperty("--bg", "var(--dark-bg)");
+  window.localStorage.setItem("theme", "dark");
+  for (let i = 0; i < imgs.length; i += 1) {
+    imgs[i].src = imgs[i].src.replace("-light", "-dark");
+  }
+}
+
+function changeToLightTheme() {
+  theme_switcher.textContent = "turn the light off";
+  document.documentElement.style.setProperty("--border", "var(--light-border)");
+  document.documentElement.style.setProperty("--text", "var(--light-text)");
+  document.documentElement.style.setProperty("--bg", "var(--light-bg)");
+  window.localStorage.setItem("theme", "light");
+  for (let i = 0; i < imgs.length; i += 1) {
+    imgs[i].src = imgs[i].src.replace("-dark", "-light");
+  }
+}