Getting Started with NodeMCU (ESP8266) on Arduino IDE

1void setup() {   
2  // initialize inbuilt LED pin as an output.
3  pinMode(LED_BUILTIN, OUTPUT);
4}
5
6// loop function runs over and over  again forever
7void loop() {
8  digitalWrite(LED_BUILTIN, HIGH);   // turn the  LED on by making the pin 13 HIGH
9  delay(500);              // wait for a 0.5  second
10  digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the  pin 13 LOW
11  delay(500);              // wait for a 0.5 second
12}