detect support sticky

supportSticky.js

var supportSticky = (function(){
    var el = document.createElement('div');
    el.style.position = 'sticky';
    if (el.style.position === 'sticky') {
        return true;
    }
    el.style.position = '-webkit-sticky';
    if (el.style.position === '-webkit-sticky') {
        return true;
    }
    return false;
})();