ESP32 Web Page Problem

2

The BUTTONPLACEHOLDER is in the wrong place. It will be replace with HTML but it is within a Javascript block. So move out of the <script> block:

  ...
  <p><input type="range" onchange="updateSliderPWM1(this)" id="pwmSlider1" min="0" max="64" value="%SLIDERVALUE2%" step="1" class="slider1"></p>

%BUTTONPLACEHOLDER%

<script>

function toggleCheckbox(element) {
...