Setting custom headers

library(chromote)
b <- ChromoteSession$new()
# Currently need to manually enable Network domain notifications. Calling
# b$Network$enable() would do it, but calling it directly will bypass the
# callback counting and the notifications could get automatically disabled by a
# different Network event. We'll enable notifications for the Network domain by
# listening for a particular event. We'll also store a callback that will
# decrement the callback counter, so that we can disable notifications after.
disable_network_notifications <- b$Network$responseReceived(function (msg) NULL)
b$Network$setExtraHTTPHeaders(headers = list(
  foo = "bar",
  header1 = "value1"
))

# Visit a web page that prints out the request headers
b$Page$navigate("http://scooterlabs.com/echo")
b$screenshot(show = TRUE)


# Unset extra headers. Note that `list(a=1)[0]` creates an empty _named_ list;
# an empty unnamed list will cause an error because they're converted to JSON
# differently. A named list becomes "{}", but an unnamed list becomes "[]".
b$Network$setExtraHTTPHeaders(headers = list(a=1)[0])

# Request again
b$Page$navigate("http://scooterlabs.com/echo")
b$screenshot(show = TRUE)


# Disable extra headers entirely, by decrementing Network callback counter,
# which will disable Network notifications.
disable_network_notifications()