how to create web client for duplex wcf service

Could someone help me with realization my chat web cliet? I've made wcf service based on duplex contract (i wanna create a online chat) and it works fine, if i use desktop-client. I wanna create web-client(js) which also let someone use the chat service. What i need to use to realize that idea? webhttpbinding with duxplex contract gives expection like: operation with ref and out parameters does not support. Thank you!