I know this question was asked many times, but I haven't found answer. So why its recommended to include scripts at the end of body tag for better rendering?
From Udacity course https://www.udacity.com/course/ud884 - rendering starts after DOM and CSSOM are ready. JS is HTML parse blocking and any script starts after CSSOM is ready.
So if we got:
<html>
<head>
<meta name="viewport" content="width=device-width,initial-scale=1">
<title>CRP</title>
<link rel="stylesheet" href="styles.css">
</head>
<body>
<!-- content -->
<script src="script.js"></script>
</body>
</html>
CRP would be:
CSSOM ready > JS execute > DOM ready > Rendering
And if script is at head:
<html>
<head>
<meta name="viewport" content="width=device-width,initial-scale=1">
<title>CRP</title>
<link rel="stylesheet" href="styles.css">
<script src="script.js"></script>
</head>
<body>
<!-- content -->
</body>
</html>
CRP would be the same:
CSSOM ready > JS execute > DOM ready > Rendering
This question is only about "sync" scripts (without async/defer attribute).
See Question&Answers more detail:
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