anyone can explain why this happened

Question

I'm making background slide automatically when I console it with console.log () why the result is only 0 and 1 why please explain to me because I confused why it can happen
https://code.sololearn.com/WhjrhP529azN/?ref=app

Answer 1

setInterval(function(){
if(current >= allimages.length-1){
current = 0;
console.log(current)
}else{
console.log(++current)
};