added slider for led brightness

data/range-input.js

@@ -0,0 +1,14 @@
+document.querySelector("form").addEventListener("input", (event) => {
+    if (event.target.classList.contains("range")) {
+        updateValue(event.target);
+    }
+});
+
+function updateValue(slider) {
+    const percentage = Math.round((slider.value / slider.max) * 100);
+    slider.nextElementSibling.innerText = `${percentage}%`;
+}
+
+document.querySelectorAll("input[type='range'].range").forEach((element) => {
+    updateValue(element);
+});