param target returns export function isObject < T = object > ( target ) { return target != null && typeof target == 'object' ; } param target returns export function isUndefined ( target ) { return typeof target == 'undefined' ; } param callback param obj returns export function mapObject < T , V , R = Record < string , V > > ( callback , obj ) { return Object . keys ( obj ) . reduce ( ( acc , key ) => { const [ k , v ] = callback ( key , obj [ key ] ) ; acc [ k ] = v ; return acc ; } , { } ) as R ; }