How To Defer Parsing Javascript in WordPress

I have seen many places recommending defering javascript.

I found this code to install in the functions.php file:
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// Defer Javascripts
// Defer jQuery Parsing using the HTML5 defer property
if (!(is_admin() )) {
function defer_parsing_of_js ( $url ) {
if ( FALSE === strpos( $url, ‘.js’ ) ) return $url;
if ( strpos( $url, ‘jquery.js’ ) ) return $url;
// return “$url’ defer “;
return “$url’ defer onload='”;
}
add_filter( ‘clean_url’, ‘defer_parsing_of_js’, 11, 1 );
}

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Do you think this would be ok to add?