layer 弹窗 弹出层 iframe子页面获取父级页面id

iframe页面：

<img id='file_url' src='http://www.paidad.cn'/>

<button id='get_pid'>获取父页面id</button>

<script src="http://libs.baidu.com/jquery/1.9.1/jquery.min.js"></script>
<script src="/js/array.js"></script>

<script>
$('#get_pid').on('click', function(){
    $('#file_url').prop('src')
    alert($(window.parent.document).find("#for_iframe").prop('src'));
});
</script>

父页面：

<img id='for_frame' src='http://www.paidad.cn'/>

<script>
$('#newsuploadimage').on('click', function(){
        layer.open({
            type: 2,
            title: '上传资讯图片',
            shadeClose: false,
            shade: 0.8,
            area: ['600px', '400px'],
            content: 'http://sjl_h5.uhuibao.cn/news/upload.html',
            cancel: function(index){
                var img_url = $(window.frames["layui-layer-iframe"+index].document).find("#newval").val()
                $("#getval").val(img_url);
                layer.close(index); 
            }
        });
});
</script>