@shopify/shopify-api/lib/utils/get-hmac-key.ts

Shopify API Library for Node - accelerate development with support for authentication, graphql proxy, webhooks

export function getHMACKey(key: string): Uint8Array {
  const arrayBuffer = new Uint8Array(key.length);
  for (let i = 0, keyLen = key.length; i < keyLen; i++) {
    arrayBuffer[i] = key.charCodeAt(i);
  }

  return arrayBuffer;
}