layui.jsでグローバル変数を宣言する方法

case 'detail':
                  if (data.length === 0) {
                    layer.msg('请选择一行');
                  } else if ( data[0].projectId ) {
                    parent.layer.open({
                      type: 2,
                      anim:1,
                      title: '查看详情',
                      maxmin: true,
                      area: ['85%', '95%'],
                      content: '/static/views/iframe/project/detail.html?projectId='+data[0].projectId +'&t='+ Date.now(),   //在链接上加入项目id,在子页面截取
                      success: function (layero, index) {  //projectId 在子页面截取，全局使用！
                        var body = parent.layer.getChildFrame('body', index);
                        // body.find('#projectId').val(data[0].projectId)
                      }
                    });
                  }else{
                    layer.msg('请刷新页面,再次操作即可')
                  }
                    break;

//这段代码通用：
var url = location.search; //获取url中"?"符后的字串
    var theRequest = new Object();
    if (url.indexOf("?") != -1) {
      var str = url.substr(1);
      strs = str.split("&");
      for (var i = 0; i < strs.length; i++) {
        theRequest[strs[i].split("=")[0]] = unescape(strs[i].split("=")[1]);
      }
    }
    var $proId = theRequest.projectId;  //声明全局项目id