Help me how to convert?

ButterChicken

C0FPacketConfirmTransaction packetConfirmTransaction = (C0FPacketConfirmTransaction)event.getPacket();

From the above code, how to modify it into javascript code?

As丶One

var C0FPacketConfirmTransaction = Java.type("net.minecraft.network.play.client.C0FPacketConfirmTransaction")
module.on("packet",function(event){
        if(event.getPacket() instanceof C0FPacketConfirmTransaction){
            var packetConfirmTransaction = event.getPacket()
            //your codes
        }
})

commandblock2

just remove the type C0FPacketConfirmTransaction then. Since JavaScript is a dynamically typed language, the type is determined at runtime. If the packet is a instance of a C0FPacketConfirmTransaction you can call getWindowId() and getUid() then if it is not, exceptions should be thrown.

//if (event.getPacket() instanceof C0FPacketConfirmTransaction)
    packetConfirmTransaction = event.getPacket();