400 Bad Request错误

JS片段
$().ready(function() {
// 设置modal 窗体的高度
    parent.$('#embed_ifame').css({"height":"500px","width":"600px"});
    parent.$('#modal-content').css("width", "650px");
   
   var contextPath = "<%=request.getContextPath()%>";
    var category_id = "${standard.productCategory.id}";
   
    initToolbarBootstrapBindings();
    $('#editor').wysiwyg({ fileUploadError: showErrorAlert} );
   
    var $select = $("#product_category_select2").select2({
        language: "zh-CN",
        width: "100%",
        theme: "classic",
        placeholder: "选择一个分类",
    });

    // 用ajax的方法获取所有的分类信息
    $.ajax({
        type: 'GET',
        url: contextPath + "/product_categories/category_select2.json",
        dataType: 'json',
        success: function(data) {
            var jsonobj = JSON.stringify(data);
            console.debug("jsonobj=="+jsonobj);
            for (var i = 0; i < data.length; i++) {
                if (data[i].id == category_id) {
                    $select.append("<option selected = 'selected' value="+ data[i].id +">" + data[i].name + "</option>");
                } else {
                    $select.append("<option value="+data[i].id +">" + data[i].name + "</option>");
                }

            }
        },
        complete: function(XMLHttpRequest, textStatus) {
        },
        error: function(event, jqxhr, settings, thrownError) {
            console.debug(event);
            console.debug(jqxhr);
            console.debug(settings);
            console.debug(thrownError);
        }
    });
})

报400错误
将<script>
    var contextPath = "<%=request.getContextPath()%>";
    var category_id = "${standard.productCategory.id}";
</script>
放在HTML中错误就会消失