Make Sure Element is Visible and Displayed : Javascript

function makeVisible(id) {
 if($('#'+id).css('display') == 'none') {
 $('#'+id).css('display','block');
 }
 if($('#'+id).css('visibility') == 'hidden') {
 $('#'+id).css('visibility','visible');
 }
 console.log('makeVisible visibility '+$('#'+id).css('visibility'));
 console.log('makeVisible display  '+$('#'+id).css('display'));
}

function testPreviewImage() {
 makeVisible('Preview_Div');
 makeVisible('Preview_Image');
 $('#Preview_Div').zIndex(16777261);
 $('#Preview_Image').zIndex(16777271);
}