Js comparison of between hours : In my app i want to determine if `hour:minute one` is biger than 21:00h and `hour:minute two` is lesser than 08:00

Am using 24h format for this. 

    var one = "21:30";
    var two = "09:51";

To get just hour from hour and minuts i use `split()`.

    var h_1 = one.split(":"); //21
    var h_2 = two.split(":"); // 08
    
        if(h1 > "21" && h2 < "08") {
            // do somthing
        }

The real story for app is : 
Shop has option for delivery out of working time. 
Working hours start at "08:00" - "21:00". If a customer wants to buy out of hours `do somthing`

So how this my example has problem and not work properly. Any better example to compare just hour and minutes between two h:m.