Update online.html

online.html

@@ -355,7 +355,14 @@
 
 
 
-
+<script>
+  document.getElementById("pH_set_but").addEventListener("click", function() {
+    var pHValue = document.getElementById("pH_set").value;
+    var xhr = new XMLHttpRequest();
+    xhr.open("GET", "/pH_set?value=" + pHValue, true);
+    xhr.send();
+});
+</script>