A promise does not have bindable properties. This controller tracks the state of a promise with bindable properties so you can create a substitution that binds the viewed component with the state of the promise.

• "pending" with "progress"

  when in the pending state, bind the substituted component to the
  progress value, which is null when indeterminate or a 0-1 value
  when determinate. Most promises are indeterminate due to the
  complexities of composing progress information into meaningful
  data.

• "fulfilled" with "value"

  when in the fulfilled state, bind the substituted component to the
  value.

• "rejected" with "error"

  when in the rejected state, bind the substituted component to the
  given error, if you can surface that error to the user.

• "state" (one of "pending", "fulfilled", or "rejected")

  suitable for substitutions that will always render an indeterminate
  progress in the "pending" state.

• "progressState" (one of "determinate", "indeterminate", "fuilfilled", "rejected")

  suitable for substitutions that provide alternative view for
  determinate and indeterminate progress.