NodeMCU esp8266 and Gauges help Please!

Hi all!
I need guidance and much needed help.
I have been on this project for almost 3-1/2 months now.
I don’t have much experience in coding or programing, all I have learned is thanks to this and many other forums alike.

The project consist on the NodeMCU ESP8266, it uses the Arduino IDE!
what I would like to do is get an ADC reading send it to the server then display that data to a Gauge.
This module is web server ready along with WIFI.

So far this is what I was able to accomplish:

as you can see, I can get the ADC reading to display in the serial monitor but not on the gauge.

there are 2 files, First the Ino that is loaded to the esp8266 and then the Index.html that is loaded to the SPIFF.

Forum.ino (3.21 KB)

Forgot the Index.html that loads the gauge!

index .txt (11.6 KB)

 /* ESP8266 SPIFFS HTML Web Page with Java and CSS 
 * Wifi-AP MODE
 * 01/26/2019
 */
 
#include <ESP8266WiFi.h>
#include <ESP8266WebServer.h>
#include <FS.h>   //Include File System Headers
 
const char* htmlfile = "/index.html";
 
          //WiFi Connection configuration
const char *ssid = "My Wifi";
const char *password = "123456789";
 
  ESP8266WebServer server(80);
 
void handleADC(){
  int a = analogRead(A0);
  a = map(a,0,1023,0,100);
  String adc = String(a);
  Serial.println(adc);
  server.send(200, "text/plane",adc); //sends data to server
}
 
void handleRoot(){
  server.sendHeader("Location", "/index.html",true);   //Redirect to our html web page
  server.send(302, "text/plane","");
}
 
void handleWebRequests(){
  if(loadFromSpiffs(server.uri())) return;
  String message = "File Not Detected\n\n";
  message += "URI: ";
  message += server.uri();
  message += "\nMethod: ";
  message += (server.method() == HTTP_GET)?"GET":"POST";
  message += "\nArguments: ";
  message += server.args();
  message += "\n";
  for (uint8_t i=0; i<server.args(); i++){
    message += " NAME:"+server.argName(i) + "\n VALUE:" + server.arg(i) + "\n";
  }
  server.send(404, "text/plain", message);
  Serial.println(message);
}
 
void setup() {
  delay(1000);
  Serial.begin(115200);
  Serial.println();
 
 
             //Initialize File System
  SPIFFS.begin();
  Serial.println("File System Initialized");
  Serial.print("Setting AP (Access Point)…");
  Serial.println();
 
             //Connect to wifi Network
  WiFi.mode(WIFI_AP);           //Only Access point
  WiFi.softAP(ssid, password);   //Start HOTspot 

 
      //If connection successful show IP address in serial monitor
  Serial.print("Connected to: ");
  Serial.println(ssid);
  IPAddress IP = WiFi.softAPIP();
  Serial.print("Server IP address: ");
  Serial.println(IP);
  

              //Initialize Webserver
  server.on("/",handleRoot);
  server.on("/getADC",handleADC); //Reads ADC function is called from out index.html
  server.onNotFound(handleWebRequests); //Set setver all paths are not found so we can handle as per URI
  server.begin();
  Serial.println("HTTP server started");  
}
 
void loop() {
 server.handleClient();
}
 
bool loadFromSpiffs(String path){
  String dataType = "text/plain";
  if(path.endsWith("/")) path += "index.htm";
  if(path.endsWith(".src")) path = path.substring(0, path.lastIndexOf("."));
  else if(path.endsWith(".html")) dataType = "text/html";
  else if(path.endsWith(".htm")) dataType = "text/html";
  else if(path.endsWith(".css")) dataType = "text/css";
  else if(path.endsWith(".js")) dataType = "application/javascript";
  else if(path.endsWith(".png")) dataType = "image/png";
  else if(path.endsWith(".gif")) dataType = "image/gif";
  else if(path.endsWith(".jpg")) dataType = "image/jpeg";
  else if(path.endsWith(".ico")) dataType = "image/x-icon";
  else if(path.endsWith(".xml")) dataType = "text/xml";
  else if(path.endsWith(".pdf")) dataType = "application/pdf";
  else if(path.endsWith(".zip")) dataType = "application/zip";
  File dataFile = SPIFFS.open(path.c_str(), "r");
  if (server.hasArg("download")) dataType = "application/octet-stream";
  if (server.streamFile(dataFile, dataType) != dataFile.size()) {
  }
 
  dataFile.close();
  return true;
}

OP's link, but clickable.

On the bowser on the tablet, what if you request the page <hotspot_ip_address>/getADC ?