I tried the tutorial at this link
My code is
<!DOCTYPE html>
<html>
<head>
<link href="cropper.css" rel="stylesheet" />
</head>
<body>
<img id="teh" src="image.png" />
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
<script src="cropper.js"></script>
<script>
$("#teh").cropper();
</script>
</body>
</html>
But, it hits error Uncaught TypeError: $(...).cropper is not a function
at $("#teh").cropper();
Found the solution already. I need to add
<script src="jquery-cropper.js"></script>
so, it becomes
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
<script src="cropper.js"></script>
<script src="jquery-cropper.js"></script>