var str ="Rome was not built in a day";
str =str.replace(/\s/g, "");
var sum =0;
for(var i of str)
{
sum++;
}
document.write(sum);
<!DOCTYPE html>
<html>
<head>
<meta charsrt="utf-8" />
<title></title>
</head>
<body>
<script>
</script>
</body>
</html>