после загрузки страницы

index.html

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>New Page</title>
<script>
window.onload=function() {
/*2 run*/
alert('Hello World!');
}
</script>
</head>
<body>
<h1>Привет Мир!</h1>
<script>
/*1 run*/
alert('To be or not to be?');
</script>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>New Page</title>
<script>
window.onload=function() {
/*2 run*/
alert('Hello World!');
}
</script>
</head>
<body>
<h1>Привет Мир!</h1>
<script>
/*1 run*/
alert('To be or not to be?');
</script>
</body>
</html>