Observable

Mike Bostock

Lightweight interface components for exploring data and building interactive displays

Observable Inputs

It looks like passing "value" to set a default selection does not work when you pass an array of objects such as in this case. Even if setting something like value: "Lakers" will not work and the default value for the variable will be null.

A radio only takes a single value, so you need to say {value: teams[0]} if you want to set the initial value to the Lakers below. If you use Inputs.checkbox instead of Inputs.radio, you can set the value to an array.