let idCounter = 0 ; export function isFunction ( value ) { return typeof value === 'function' ; } export function isString ( value ) { return typeof value === 'string' ; } export function noop ( ) { } export function pick < T , K extends keyof T > ( obj , keys ) { const result = { } ; keys . forEach ( ( key ) => { result [ key ] = obj [ key ] ; } ) ; return result ; } export function uniqueId ( prefix ? ) { idCounter += 1 ; return ( prefix == null ? '' : String ( prefix ) ) + idCounter ; }