5v sonar (HC-SR04) and distance sensing robot example

Hi, everybody.

I am new to Espruino, and I would like to build a little robot like the distance sensing one.

There is a thing I don't understand about the sonar. The source code reads:

var TRIG = A0; // ultrasonic trigger
var ECHO = A1; // ultrasonic echo signal

but one should avoid connecting 5v input to the pins marked as '3.3v'.

Now, the sonar used in the example is a HC-SR04, and its output is set to 5V. Shouldn't it be connected to one of the general purpose I/O pins, chosing one which is NOT marked as 3.3V?

L.