Edit in JSFiddle

$(document).ready(function() {

    var div = document.createElement('div');
    div.setAttribute('style','position:absolute; left:-999px;');
    var el = document.createElement('span');
    
    div.appendChild(el);
    document.body.appendChild(div);
    
    alert(getComputedStyle(el, null).getPropertyValue('display').toString());
});