Hide/Unhide Element Via ID

In this code it is important to have visibility = ‘hidden’ and display = ‘none’ to hide without leaving white space

function off(i) {
    document.getElementById(i).style.visibility = 'hidden';
    document.getElementById(i).style.display = 'none';
}

In this code it is important to have visibility = ” and display = ” to show

function on(i) {
    document.getElementById(i).style.visibility = '';
    document.getElementById(i).style.display = '';
}