Derive the constraint-hint descriptor for a field at inputId. Returns undefined when the field has no constraint worth announcing — callers skip rendering the <small> element entirely rather than emitting an empty node.
inputId
undefined
<small>
Derive the constraint-hint descriptor for a field at
inputId. Returnsundefinedwhen the field has no constraint worth announcing — callers skip rendering the<small>element entirely rather than emitting an empty node.