var slideContainer = ('#slider');
var width = 720;
var clicked = false;
function slide () {
if ( clicked ) return;
clicked = true;
if (parseInt( $slideContainer.css('marginLeft') ) >= -2160 ) {
$slideContainer.animate({'margin-left': '-='+width},200,"linear",()=>{
clicked=false;});
}
}
<a class='button' onclick='slide()'></a>