We will describe to you how to check file size before uploading the image on the server using jQuery.


 $(function() {
                $('#image').change(function() {
                    if (Math.round(this.files[0].size / (1024 * 1024)) > 2) {
                        alert('Please select image size less than 2 MB');
                    } else {
                        alert('success');
                    }
                });
            });


If the file size greater than 2MB then it will return the error messages otherwise return the success message.


#complete_code.html

<!DOCTYPE html>
<html lang="en">
    <head>
        <title>jQuery Tutorial</title>
        <meta charset="utf-8">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/css/bootstrap.min.css">
        <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
        <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/js/bootstrap.min.js"></script>
        <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js"></script>
        <script>
            $(function() {
                $('#image').change(function() {
                    if (Math.round(this.files[0].size / (1024 * 1024)) > 2) {
                        alert('Please select image size less than 2 MB');
                    } else {
                        alert('success');
                    }
                });
            });
        </script>
    </head>
    <body>
        <div class="container">
            <form method="post" name="frmAdd" id="frmAdd">
                <div class="form-group">
                    <label for="image">Image:</label>
                    <input type="file" name="image" class="form-control" id="image" value="">
                </div>
                <button type="submit" class="btn btn-default">Submit</button>        
            </form>
        </div>
    </body>
</html>