pinMode(pin, [INPUT | OUTPUT | INPUT_PULLUP | INPUT_DOWN])
digitalWrite(pin, [HIGH | LOW])
digitalRead(pin)

Example:

function setup() {
  pinMode(D0, OUTPUT);
  pinMode(D34, INPUT);
}

function loop() {
  let value = digitalRead(D34);
  digitalWrite(D0, value);
}

Similar to Arduino, these commands configure, write and read a digital GPIO pin.

The possible values for pin are: