src/basis/tracker.js
function isVisible(element){
    if (getComputedStyle(element, 'visibility') != 'visible')
      return false;

    var box = getBoundingRect(element);

    if (!box.width || !box.height)
      return false;

    return true;
  }
function isVisible(element){
    if (getComputedStyle(element, 'visibility') != 'visible')
      return false;

    var box = getBoundingRect(element);

    if (!box.width || !box.height)
      return false;

    return true;
  }
function isVisible ( element ) { if ( getComputedStyle ( element , 'visibility' ) != 'visible' ) return false ; var box = getBoundingRect ( element ) ; if ( ! box . width || ! box . height ) return false ; return true ; }
Checks visibility of an element on a page in a browser
@param {HTMLElement} element some DOM node
@private
@return {boolean}
Checks visibility of an element on a page in a browser