Add log or graph to wifiserver?

Hi there. This is my first go at messing with one of these things, so I'm a little impressed I got as far as I have. This gives me an IP I can go to and see a battery voltage. As it is, it seems to work ok. I'm really looking to see if there's some way to have it keep track of the voltage value with a timestamp. I see that there's a way to connect a sd card module to it and have it log to a file on there, so I might order some of those and give that a shot later, but for now I'd be happy if it just had a running log of time and voltage value every so many seconds that displayed on that web page for as long as I had it open or something. Any ideas?


/*****************************************************
   Date: 18 june 2018
   Written by: Usman Ali Butt
   Property off: microcontroller-project.com
 * ***************************************************/
#include <ESP8266WiFi.h>

const char* ssid = "**********";
const char* password = "**********";
const int voltageSensor = A0;

float vOUT = 0.0;
float v = 0.0;
float R1 = 30000.0;
float R2 = 7500.0;
int value = 0;
WiFiServer server(80);

void setup() {
  Serial.begin(9600);
  delay(10);
  Serial.print("Connecting to ");
  Serial.println(ssid);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");
  server.begin(); // Start the server
  Serial.println("Server started");
  // Print the IP address on serial monitor
  Serial.print("Use this URL to connect: ");
  Serial.print("http://");    //URL IP to be typed in mobile/desktop browser
  Serial.print(WiFi.localIP());
  Serial.println("/");
}

void loop() {
  int value = LOW;
  float v = 0.0;
  float vOUT = 0.0;

  // Check if a client has connected
  WiFiClient client = server.available();
  if (!client) {
    return;
  }

  // Wait until the client sends some data
  Serial.println("new client");
  while (!client.available()) {
    delay(1);
  }

  // Read the first line of the request
  String request = client.readStringUntil('\r');
  Serial.println(request);
  client.flush();

  // Match the request

  if (request.indexOf("/bat=ON") != -1)  {
    /////////////////////////////////////Battery Voltage//////////////////////////////////
    value = analogRead(voltageSensor);
    vOUT = (value * 3.09) / 1024.0;
    v = vOUT / (R2 / (R1 + R2));
    /////////////////////////////////////Battery Voltage//////////////////////////////////
    value = HIGH;
  }

  // Return the response
  client.println("HTTP/1.1 200 OK");
  client.println("Content-Type: text/html");
  client.println(""); //  do not forget this one
  client.println("<!DOCTYPE HTML>");
  client.println("<html>");

  client.println("Battery Voltage =");
  client.print(v);
  client.println("<br>");

  if (value == HIGH) {
    client.println("Updated");
  } else {
    client.print("Not Updated");
  }
  client.println("--------");
  if (v <= 5) {
    client.println("Battery dead OR disconnected");
  }
  else if (v > 5 && v <= 10) {
    client.println("Need Imediate recharge");
  }
  else if (v > 10 && v <= 12) {
    client.println("Recharge");
  }
  else {
    client.println("Battery Full");
  }

  client.println("<br><br>");
  client.println("<a href=\"/bat=ON\"\"><button>Status</button></a><br />");
  client.println("</html>");
  delay(1);
  Serial.println("Client disconnected");
  Serial.println("");

}

maybe my TelnetStream library has what you want. it is in Library Manager.