Follow this link for footlocker, eastbay and champs. 
http://moourl.com/4d229

window.addEventListener('load', function() {

var added = false;

function interval1(){
return  window.setInterval(function(){
        if(document.getElementById("addToCart") !==  null){
            added = true;
            window.location = "http://www.footaction.com/checkout/";
        }
        else if(added === false){
            var cartbtn = document.getElementById("addToCartLink");
            cartbtn.click();
        }
    }, 1000);
}

var id1 = interval1();

window.setInterval(function(){
   if(added === true){
    window.clearInterval(id1);
   }
}, 100);

});