An example of how to verify a message signature with Near api js

verifySignatureNear.js

const nearApi = require("near-api-js");
const { sha256 } = require("js-sha256");

const run = async () => {
  const keyPairA = nearApi.utils.key_pair.KeyPairEd25519.fromRandom();
  const publicKeyAString = keyPairA.getPublicKey();
  const keyPairB = nearApi.utils.key_pair.KeyPairEd25519.fromRandom();

  const publicKeyA = nearApi.utils.key_pair.PublicKey.from(publicKeyAString);

  const message = new Uint8Array(sha256.array("message"));
  const signature = keyPairA.sign(message);

  console.log(keyPairA.verify(message, signature.signature)); // true
  console.log(keyPairB.verify(message, signature.signature)); // false
  console.log(publicKeyA.verify(message, signature.signature)); // true
};

run();