ESP8266 Arduino OTA example v1

OTATest.ino

#include <ESP8266WiFi.h>
#include <WiFiUDP.h>

const char* ssid = "..........";
const char* password = "...........";

WiFiUDP listener;

void setup() {
  Serial.begin(115200);
  Serial.setDebugOutput(true);
  Serial.println("");
  Serial.println("OTA test");
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("Connected to ");
  Serial.println(ssid);
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());

  listener.begin(8266);

  Serial.print("Sketch size: ");
  Serial.println(ESP.getSketchSize());
  Serial.print("Free size: ");
  Serial.println(ESP.getFreeSketchSpace());
}

void loop() {
  int cb = listener.parsePacket();
  if (cb) {
    IPAddress remote = listener.remoteIP();
    int cmd  = listener.parseInt();
    int port = listener.parseInt();
    int sz   = listener.parseInt();
    Serial.println("Got packet");
    Serial.printf("%d %d %d\r\n", cmd, port, sz);
    WiFiClient cl;
    if (!cl.connect(remote, port)) {
      Serial.println("failed to connect");
      return;
    }

    listener.stop();

    if (!ESP.updateSketch(cl, sz)) {
      Serial.println("Update failed");
    }
  }

  delay(100);
}

@bkrajendra : in arduino IDE -> Tools > port. Your esp should appear in this section under "network ports". But I doesn't upload for me
(sorry if bad englsih, I'm french)

To specify IP instead of serial port (in case it does not appear in the list):
File > Prefrences will show your preferences file
C:\Users\AppData\Roaming\Arduino\preferences.txt
Edit with IP of esp module, for example :
serial.port=192.168.0.50
Restart Arduino and check bottom-right corner to see your IP is displayed