The CryptoKey.algorithm read-only property is an opaque value containing all the information about the algorithm related to the key.
The CryptoKey.extractable read-only property that indicates if the raw material key can be extracted, for example for archiving it.
The CryptoKey.type read-only property that indicates the type of the key: if it is the key for a symmetric algorithm ("secret") or for an asymmetric algorithm ("public" or "private", depending of its purpose).
The CryptoKey.usages read-only property is an array of enumerated that indicates the purposes of the key.