Recharge JS add to cart and redirect to checkout

recharge.js

  //recharge redirect to checkout
  function reChargeProcessCart() {
    function get_cookie(name){ return( document.cookie.match('(^|; )'+name+'=([^;]*)')||0 )[2] }
    do {
      token=get_cookie('cart');
    }
    while(token == undefined);

    var myshopify_domain='{{ shop.permanent_domain }}'
    try { var ga_linker = ga.getAll()[0].get('linkerParam') } catch(err) { var ga_linker ='' }
    var customer_param = '{% if customer %}customer_id={{customer.id}}&customer_email={{customer.email}}{% endif %}'
    checkout_url= "https://checkout.rechargeapps.com/r/checkout?myshopify_domain="+myshopify_domain+"&cart_token="+token+"&"+ga_linker+"&"+customer_param;
  	window.top.location.href= checkout_url;
  }
  
  
  //recharge add to cart
  function addItemToCart(variant_id, qty, frequency, unit_type) {
    data = {
      "id": variant_id,
      "quantity": qty,
      "properties": {
        "shipping_interval_frequency": frequency,
        "shipping_interval_unit_type": unit_type
      }
    }
    jQuery.ajax({
      type: 'POST',
      url: '/cart/add.js',
      data: data,
      dataType: 'json',
      success: function() { 
        //window.top.location.href = '/cart'; 
        reChargeProcessCart()
      },
      error: function(data){
      	console.log(data);
      }
    });
  }