ECDSA how to derive public key from private key using web crypto api javascript

getPublicKeyFromPrivateKey.js

// Inspired/copied from : https://stackoverflow.com/questions/72151096/how-to-derive-public-key-from-private-key-using-webcryptoapi
async function getPublicKeyFromPrivateKey(privateKey) {
    const jwkPrivate = await crypto.subtle.exportKey("jwk", privateKey);
    delete jwkPrivate.d; // this trick makes the jwk a public key!
    jwkPrivate.key_ops = ["verify"];
    const publicfromprivate = await crypto.subtle.importKey("jwk", jwkPrivate, {name: "ECDSA", namedCurve: "P-256"}, true, ["verify"]);
    const publicKey = await crypto.subtle.exportKey('spki', publicfromprivate);
    return publicKey;
}

It's not possible to derive a public EC P-256 key directly using crypto.subtle, but you can export the private key as a JWK, then delete the private key and reimport the JWK as your EC P-256, which creates a public key from your private key! Boom!