simple explanation how to save code that espruino run on start?

hi @allObjects , thanks for your quick response and recommendations. I just want to clarify two things.

1. The code below runs perfectly, but it does not run in the form I described above.

   var toggle=1;
   setInterval(function() {
   toggle=!toggle;
   digitalWrite(D5, toggle);
     
   console.log(toggle);
   }, 1000);
   

2. As you assumed, I write my code in the right pane and upload it. Then I say save() in the left pane. I can see onInit() gets called and the console logs true, false.... I mean everything works as expected except digitalWrite()