Array

Boa tarde! Help:

estou tentando chegar neste valor value: ['Basic am9yZ2U6cGVkcmluaG9AMTIz']e nao estou conseguindo algume pode ajudar?

const req = request.headers;

 console.log('intercept: ', req) = 

HttpHeaders {normalizedNames: Map(2), lazyUpdate: null, headers: Map(2), lazyInit: null}
headers: Map(2)
[[Entries]]
0: {"authorization" => Array(1)}
key: "authorization"
value: ['Basic am9yZ2U6cGVkcmluaG9AMTIz']
1: {"content-type" => Array(1)}
size: 2
[[Prototype]]: Map
lazyInit: null
lazyUpdate: null
normalizedNames: Map(2) {'authorization' => 'Authorization', 'content-type' => 'Content-Type'}
[[Prototype]]: Object