Here we use an Adafruit Circuit Playground Express (CPX) which has the following characteristics:

• Has a transmit IR LED with a wide field of view and good transmit power
• CPX shows up on your computer as a USB flash drive when connected via a power+data USB cable
• CPX is programmable via CircuitPython, a language that is easy to use and code that can be changed quickly without installing a toolchain (like Arduino) and changes do not require recompile, just copy a new code file onto CPX and it runs.

Parts List

Build

Hook up the Circuit Playground Express as shown below. When using the USB cable, you don't need the battery pack connected.

For programming and testing, you don't need the battery pack connected, the USB cable will power the Circuit Playground Express and allow for programming. 

When programming is complete and you want a stand-alone controller, disconnect the USB cable and plug in the battery pack which has 3 AA cells in it. There is an on/off switch on the battery pack. Note the switch on the Circuit Playground Express is not a power switch.