Getting started with the NodeMCU devkit on OSX (for version 1.0):

• You will need to install the SiLabs serial driver for the chip (direct link)

• To connect to it, first install CoolTerm

  • pick Options, then select the /dev/cu.SLAB_USBtoUART connection that those drivers created.
  • 9600 baud worksforme

• If on connection, the device says "Please run file.remove("user.lua") before first use." in a loop, enter the commands:

  file.remove("user.lua")
  node.restart()
  

• CoolTerm is good for direct simple communication, but for working with the device you want ESPlorer and its associated eBook by Rui Santos.

• To flash the firmware you need special flags.

  • Get the appropriate NodeMCU firmware

  • Install esptool:

    git clone https://github.com/themadinventor/esptool.git 
    cd esptool
    sudo python ./setup.py install
    

  • Hold down the "FLASH" button on the device and hit the "RST" button while doing so.

  • Substituting in the correct path to the firmware file you downloaded, run

    python ./esptool.py --port=/dev/cu.SLAB_USBtoUART  write_flash  -fm=dio -fs=32m 0x00000 ../nodemcu-master-8-modules-2015-09-01-02-42-13-float.bin
    

  • Unplug the device and replug it.

  • Connect for great justice

Happy Hacking!

Thanks to François Guillier for figuring most of this out!

Please note: If you have the older NodeMCU dev kit version (blue silkscreen, says Devkit 0.9 on the silkscreen) try these steps:

• You'll need the WCH serial driver: https://www.wch.cn/download/CH341SER_MAC_ZIP.html
• My module did not have a reset button wired. The simplest way to flash the ESP8266 for me was to:
  • Make note of the serial port. Look out of something like: /dev/cu.wchusbserial...
  • Unplug the NodeMCU dev kit first.
  • Press the FLASH button and keep it pressed.
  • Replug the NodeMCU dev kit,
  • Wait a bit and then release the FLASH button.
  • Start the flashing process with executing the terminal commands from above.

To figure out the serial port, type in the Terminal: ls /dev/cu.*