Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

go version devel +c814ac44c0 Thu Jul 19 21:30:27 2018 +0000 darwin/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

GOARCH="wasm"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="js"
GOPATH="/Users/eginez/repos/goland"
GOPROXY=""
GORACE=""
GOROOT="/Users/eginez/repos/go"
GOTMPDIR=""
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/pm/tlg5p5nx4vj3s05h4rfsv3t40000gn/T/go-build136489492=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

The native http client, maps to the fetch() api. With the current client it is impossible to set additional options as supported by the fetch call, see: https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch.

What did you expect to see?

A way to specify options for the fetch call