Script for adding a donation product via AJAX

Donation Script

<script type="text/javascript" charset="utf-8">
//<![CDATA[
// Including jQuery conditionnally.
if (typeof jQuery === 'undefined') {
    document.write({{ "http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js" | script_tag | json }});
  document.write('<script type="text/javascript">jQuery.noConflict();<\/script>');
}
//]]>
</script>

<script>
{% assign linklist = linklists['donation'] %}
var id = {{ linklist.links.first.object.variants.first.id }};

$(document).ready(function () {
   $('input[name="checkout"], input[name="goto_pp"], input[name="goto_gc"]').click(function(e) {
    e.preventDefault();
    var amount = $('#donate').val();
    
    amount = amount * 100;
    amount = parseInt(amount);
    
    function addDonation(){
        var params = {
    	               type: 'POST',
					url: '/cart/add.js',
					data: 'quantity='+amount+'&id='+id,
					dataType: 'json',
					success: function(line_item) { 
            document.location.href = '/checkout';
					},
					error: function() {
					}
				};
	    $.ajax(params);
    }
    addDonation();
    });
});
</script>