html.pngHTML

<!DOCTYPE html>
<html>
    <head>
        <link href="style.css" rel="stylesheet">
        <script src="script.js" async defer></script>
    </head>
    <body>
        <script src="jquery.js"></script>
        <img src="html.png">
        <img src="watch.png">
    </body>
</html>

Characteristics of this page

Even though the script.js is placed in the <head> with async to be executed asynchronously, the later jquery.js blocks it. As a result, script.js could not be executed until almost onload. This example indicates that dependencies and priority should be taken carelully into consideration.

watch.pngObject Event Timeline