How to filter ag grid by month in mm-yyyy format

I have an ag grid table and I trying to filter it by month mm-yyyy how can i do that??

this is how i am filtering by month

params.request.filterModel.bookingTime = {
                    dateFrom: this._month +"-01"+' 00:00:00',
                    dateTo: this._month +"-28"+ ' 23:59:59',
                    type: 'inRange',
                    filterType: 'date'
                }

but it is not giving me proper result .