JS 方法调用问题

Question

script.js

(function($){

    layer.config({
    skin:'layer-ext-moon',
    extend:'skin/moon/style.css'
    });

    var $layer_load;

    //屏蔽form submit 方法
    $("form").on("submit", function(){ return false;});

  //扫码
  function do_scan($scan_id) {

    $params = $.param({
          scan_id: $scan_id
        });

        $.ajax({
          type: 'post',
          dataType: 'json',
          data: $params,
          url: $url,
          beforeSend: function() {
            $layer_load = layer.load();
          },
          success: function(data) {
            layer.close($layer_load);
            console.log(data);

            if(data.err_no == 0) {

              var tpl = $("#scan-tpl").html();
              laytpl(tpl).render(data.results, function(html){
                $("#scan-box").html(html);
              });
            } else {

              layer.alert(data.err_msg, {icon: 2});
              return false;
            }
          }
        });
  }


  $("#text-scan").on("keyup", function(event){

    if( event.keyCode == 13 || event.keyCode == 108) {

        $url = $(this).data('url');
        $scan_id = $.trim( $(this).val());

        if( $scan_id == '') {
          layer.alert('请输入扫入条码');
          return false;
        }
        
        $(this).val('');

        do_scan($scan_id);
    }
  });


  var $this = this;
  wx.ready(function(){
    wx.hideAllNonBaseMenuItem();

    //点击调用微信扫描
    $("#btn-scan").on('click', function(){
      wx.scanQRCode({

        needResult: 1,
        scanType: ["qrCode","barCode"],
        success: function (res){

          var result = res.resultStr;

          result = result.substring( result.lastIndexOf(',') + 1);
          $("#text-scan").val(result);
          $this.do_scan(result); //这个do_scan 就是不执行
        },
        cancel: function() {
          layer.alert('您取消了使用微信扫码！',{icon: 5});
        }
      });
    });
  }); //wx.ready End
})(jQuery);

估计是调用JS类外方法的问题，谢谢大神！ -_-||