The probably shortest way to convert milliseconds in HH:mm would be:

let timeInMilliseconds = 33000000 let timeInHHmm = ${Math.round(timeInMilliseconds/3600/1000)}h ${Math.round(((timeInMilliseconds/3600 / 1000)-(Math.round(timeInMilliseconds/3600/1000)))*60)}m;

console.log(timeInHHmm)