timer

by Yuriy Petrichenko

HTML

<h1></h1>

CSS

h1{
  color:#333;
 background:springgreen;
 text-align:center;
}

JavaScript

var txt = document.querySelector("h1");
var count = 0;
var timer;
function counter(){
 txt.innerHTML=count;
  count ++;
  if(count==321){
clearInterval(timer);

}
}
function r(){
timer= setInterval(counter,1000);
}
r();