console
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
</head>
<body>
<script>
var sum=0;
for(i=1;i<=100;i++){
sum+=i;
}
document.write(sum);
</script>
</body>
</html>
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
</head>
<body>
<script>
var sum=0;i=1;
while(i<=100){
sum+=i;
i++;
}
document.write(sum);
</script>
</body>
</html>
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
</head>
<body>
<script>
var i=1;sum=0
do{
sum+=i
i++
}
while(i<=100)
document.write(sum);
</script>
</body>
</html>