change slot of [from][to] filed into slots of range equal averageTimetime

sliceSlotsByAverageTime.js

const sliceSlotsByAverageTime =  (slots,averageTime)=>{

    let newSlots = [] ; 
    
    
    // loop over slots
    slots.forEach((slot)=>{
        let from =  new Date(slot.from);
        let end =  new Date(slot.to);
        let loop = 1 ;

        while((from.getTime() + averageTime * 1000 * 60 ) <= end.getTime() && loop++ < 9000){

          console.log(from.toString())
             let _from = new Date(from) ; 
            let _to = new Date(from.setMinutes(from.getMinutes() + averageTime)) ; 
            let freeSlot = {from:_from,to:_to};
            newSlots.push(freeSlot);
            //from.setMinutes(from.getMinutes() + averageTime);
        }
        
    });
    
    return newSlots;
    
}

let dates = [ {
            "from": "2018-01-15T09:00:00.000Z",
            "to": "2018-01-15T23:00:00.000Z",
            "serviceId": "5a35577c6fb89000141de146",
            "type": "FREE"
        },
        {
            "from": "2018-01-16T10:00:00.000Z",
            "to": "2018-01-16T23:20:00.000Z",
            "serviceId": "5a35577c6fb89000141de146",
            "type": "FREE"
        }];


freeSlotsToAverageTime(dates,30);