why can't i use setTimeout in scripts ?

[Alexandre Buisson]

var i = 0;                  

function myLoop() { 
  setTimeout(function() {  
    p422.set(p422.value + 1);
    i++;                 
    if (i <= 20) {           
      myLoop();            
    } else {
      i = 0;
    }               
  }, 400)
}
if (p420.value) {
    myLoop();
}
setInterval(function() {
        if (p420.value) {
            myLoop();
        } else {
            return false
        }
}, 8500)

I need to execute my myLoop() function indefinitely with a time between each execution. So I need to use setTimeout but it doesn't work. I have an error ReferenceError "setTimeout" is not defined.
I would like to know why, and what can I use instead?

Thank you in advance