Recently I have been playing with WebSocket, partly due to the chrome_print() function in the pagedown package. Last Friday, it suddenly occurred to me that there could be a very interesting way to improve the user experience of the “Infinite Moon Reader” in the xaringan package (i.e., xaringan::inf_mr()). After three days’ work, I have finally become happy with it:

<img src=“https://user-images.githubusercontent.com/163582/53144527-35f7a500-3562-11e9-862e-