watch 不支持在查询条件里加上正则匹配的。

这里有bug，应该在watch初始化的时候，就报错“不支持正则” 的，这里后续会完善。

//针对watcher不支持模糊检索，对change数据分别处理
.watch({
        onChange: function(snapshot) {
          //初始化时type=init
          if (snapshot.type){
            that.setData({
              list: snapshot.docs, 
            });
          }
          //更新时
          else{
            let tmpBackList = that.data.list.slice(0);
            
            for( var i = 0; i < snapshot.docChanges.length; ++i ){
              var docChange= snapshot.docChanges[i]
              var doc =docChange.doc;
              const index = tmpBackList.findIndex(item => item._id === doc._id);
              const search=doc.toDo.title.indexOf(that.data.searchStr)  //校验搜索条件    
              switch ( docChange.dataType ) {
                //记录进入列表
                case "add":
                  
                  //校验搜索条件
                  if (  search >=0  && index < 0 ){  //6-15出现重复数据 汉字多次watch，所以增加index校验
                    tmpBackList.push(doc);
                    
                  }
                  break;
                 case "replace":
                      if (index >= 0 && search >=0){ //更新
                      tmpBackList.splice(index,1,doc);  
                    }else if(index < 0 && search >=0 ){          //更新的新增
                      tmpBackList.push(doc);
                    }else if(index >= 0 && search < 0 ){          //更新的去除
                      tmpBackList.splice(index,1);
                    }
                    break;
                case "update":
                    if (index >= 0 && search >=0){ //更新
                      tmpBackList.splice(index,1,doc);  
                    }else if(index < 0 && search >=0 ){          //更新的新增
                      tmpBackList.push(doc);
                    }else if(index >= 0 && search < 0 ){          //更新的去除
                      tmpBackList.splice(index,1);
                    }
                  break;
                //记录离开列表  
                case "remove":
                  if (index>= 0){
                    tmpBackList.splice(index,1);
                    
                  }
                  break;
                //列表中的记录内容有更新，但列表包含的记录不变
                default:
                  console.log("toDay.watcher.onChange.default",doc);
              }
              
            }
                        //更新列表
                        that.setData({
              list: tmpBackList, 
            });
          }