Supplies the value a key stands for, either as a record listing the values or as a function computing them on
demand. A record leaving a key out and a function returning undefined for it alike leave the key unresolved, and
what that means is left to the operation taking the lookup.
Value lookup by key.
Supplies the value a key stands for, either as a record listing the values or as a function computing them on demand. A record leaving a key out and a function returning
undefinedfor it alike leave the key unresolved, and what that means is left to the operation taking the lookup.