gistfile1.js

        buildQuery: function() {
          var query = [];
          var name = this.username.value;
          var startDate = this.startDate.value;
          var endDate = this.endDate.value;

          if(name) {
            query.push("username LIKE '%"+name+"%'");
          }

          if(startDate) {
            query.push("time > '"+startDate+"'");
          }

          if(endDate) {
            query.push("time < '"+endDate+"'");
          }

          if(query.length > 1) {
            return query.join(' AND ');
          } else {
            return query.join('');
          }
        },