for (i = 0; i <= portfolio_div_el.length; i++) {
if (posTop > scrollPos){
   console.log(scrollPos);
   scroll_down();
} else {
   console.log(scrollPos)
    scroll_up();
}
} 
scrollPos = posTop;var scrollPos = 0; 
var portfolio_div_el = document.getElementById('portfolio').children;
function scroll_down() {
var cord_y_top = Math.round(portfolio_div_el[i].offsetTop);
if ((posTop + 500) > cord_y_top ) {
portfolio_div_el[i].style.transform = "translateY(0)";
} 
//console.log('elem' + scrollPos);
}
function scroll_up() {
var cord_y_top = Math.round(portfolio_div_el[i].offsetTop);
var el_cord_top = Math.round(portfolio_div_el[i].getBoundingClientRect().bottom + posTop); 
var el_cord_bottom = Math.round(portfolio_div_el[i].getBoundingClientRect().top + posTop); 
if (posTop > el_cord_top ) {
portfolio_div_el[i].style.transform = "translateY(0)";
} else if (posTop < el_cord_top ) {
portfolio_div_el[i].style.transform = "translateY(15px)";
} 
}
window.addEventListener('scroll', function() { 
posTop = (window.pageYOffset !== undefined) ? window.pageYOffset : (document.documentElement || document.body.parentNode || document.body).scrollTop;
for (i = 0; i <= portfolio_div_el.length; i++) {
if (posTop > scrollPos){
<b>scroll_down();</b>
} else {
<b>scroll_up();</b>
}
} 
scrollPos = posTop;
});