Unexpected output ide

To my understanding of javascript, asynchronous-like behaviour from timeout is meant to run when execution stack is empty. I expect output with 'nope' at the bottom of the list. Why is this happening? Im running in the 'web ide' with emulator mode. Tested on my bangle watch connected to the ide too, same.

setTimeout( function(){console.log("nope");},0);
console.log("yep");
console.log("yep");
console.log("yep");
console.log("yep");
console.log("yep");
var dontgetit = 345;

OUTPUT:

>yep
nope
>yep
>yep
>yep
>yep

another example :

setTimeout( function(){console.log("nope");},100);
var x =0;
while ( x < 10000 ) {
  x++;
}
  
var dontgetit = 345;
console.log("done");