Normal

<!doctype html> 
<html lang="en">
    <head>
        <meta charset="utf-8">
        <title>Example HTML5 Document Example</title>
    </head>
    <body>
        <p>Test</p>
    </body>
</html>

HTML

<!doctype html> 
<html lang="en">
    <head>
        <meta charset="utf-8">
        <title>Example HTML5 Document Example</title>
    </head>
    <body>
        <p>Test</p>
    </body>
</html>

Javascript

$(window).scroll(function(){
    if($(window).scrollTop()>300){
        $('#totoc').fadeIn(250);
    }else{
        $('#totoc').fadeOut(250);
    };
});