[layUI] layui 彈出框設置div滾動條位置

由於使用封裝好的layui組件，需要在彈出組件上指定id操作

效果：

 let layer = layui.layer;
    layer.open({
        type: 1
        ,area: ['20%','25%']
        ,id:"div_1"
        ,content: '<div id="div_v"><span>123</span></br><span>123</span></br><span>123</span></br><span>123</span></br><span>123</span></br><span>123</span></br><span>123</span></br><span>123</span></br><span>123</span></br><span>123</span></br><span>123</span></br><span>123</span></br></div>'
        ,btn: '關閉全部'
        ,btnAlign: 'c' //按鈕居中
        ,shade: 0 //不顯示遮罩
        ,yes: function(){
          layer.closeAll();
        }
      });
      let div = document.getElementById('div_1');
      div.scrollTop = div.scrollHeight;