The nrf52840-mdk can support Zephyr kernel.

Download GNU ARM Tools

Download cross tool at:

https://developer.arm.com/tools-and-software/open-source-software/developer-tools/gnu-toolchain/gnu-rm/downloads

Add the following environment variables to ~/.bash_profile:

export GNUARMEMB_TOOLCHAIN_PATH="<path to install directory>/gcc-arm-none-eabi-6-2017-q2-update"
export ZEPHYR_TOOLCHAIN_VARIANT=gnuarmemb

Download Zephyr

$ git clone https://github.com/zephyrproject-rtos/zephyr.git
$ brew install cmake ninja dfu-util doxygen qemu dtc python3 gperf
$ cd ~/zephyr
$ pip3 install --user -r scripts/requirements.txt

Add variable configs to ~/.bash_profile:

export PATH="/usr/local/opt/ncurses/bin:$PATH"
export PATH="/usr/local/opt/sqlite/bin:$PATH"

Install PyOCD

$ pip3 install -U pyocd

Build IoT Application

$ cd <path-to-zephyr>
$ source zephyr-env.sh

Install Zephyr west:

$ pip3 install west --user

Download the official nrf52840-mdk sdk and initialize the west environment:

$ git clone https://github.com/makerdiary/nrf52840-mdk
$ cd <path-to-your-nrf52840-mdk>/nrf52840-mdk/examples/zephyr/blinky
$ west init

Create a build directory and start the project build:

$ mkdir build; cd build
$ cmake -GNinja -DBOARD=nrf52840_mdk ..
$ ninja
$ ninja flash

You can use west directly:

$ cd <path-to-your-nrf52840-mdk>/nrf52840-mdk/examples/zephyr/blinky
$ west init
$ west build -b nrf52840_mdk 
$ west flash

Build JerryScript on Zephyr

$ cd jerryscript
$ make -f ./targets/zephyr/Makefile.zephyr BOARD=nrf52840_mdk