Javascript – différentes manières d’exécuter du JS

<!-- js pur et dur-->

<!DOCTYPE html>
<html>
<head>
<script>
function myFunction()
{
        document.getElementById("monbouton").onclick=function(){
                document.getElementById("demo").innerHTML="toto";
        }
}
</script>
</head>
<body>
<p>Click the button to trigger a function.</p>
<button onclick="myFunction()">Click me 1</button>
<button id="monbouton">Click me 2</button>
<p id="demo"></p>
</body>
</html>
<!-- jquery + onload -->

<!DOCTYPE html>
<html>
<head>
<script src="http://code.jquery.com/jquery-1.9.1.min.js"></script>
<script>
$(window).load(function(){
        $("#monbouton").onclick=function(){
                document.getElementById("demo").innerHTML="toto";
        }
        });
</script>
</head>
<body>
<p>Click the button to trigger a function.</p>
<button id="monbouton">Click me 2</button>
<p id="demo"></p>
</body>
</html>
<!-- jquery à la fin du code--->

<!DOCTYPE html>
<html>
<head>
<script src="jquery-1.9.1.min.js"></script>

</head>
<body>
<p>Click the button to trigger a function.</p>
<button class="test">Click me 2</button>
<p class="demo"></p>
</body>
<script>
        $('.test').click(function(){
                                $(".demo").html("toto");
                        alert('toto');

                });
</script>
</html>