Proper parameter to import ECDSA(JWK) private key

[jasonclg]

I was able to import JWK private key based on the ecPublicKey example

  const privateKey = await importJWK(
    {
      crv: "P-256",
      kty: "EC",
      x: "MKBCTNIcKUSDii11ySs3526iDZ8AiTo7Tu6KPAqv7D4",
      y: "4Etl6SRW2YiLUrN5vfvVHuhp7x8PxltmWWlbbM4IFyM",
      d: "870MB6gfuTJ4HtUnUvYMyJpr5eUZNP4Bk43bVdj3eAE",
    },
    "ES256"
  );

However, if I remove x and y (coordinates of public key), it will throw DOMException: The required JWK member "x" was missing
My question: why is public key required to import JWK private key?

[panva]

Because that's how the different specifications are defined and layered.

The JWK definition requires public key components to always be present. Web Crypto API checks the input to be a valid JWK.