This package has been strongly influenced by Chopsticks. Its usage is only recommended and supported in NodeJS environments.
At this point, it just exports a getMetadataFromRuntime function that runs WASM under the hood, and returns its metadata in string.
import { getMetadataFromRuntime } from "@polkadot-api/wasm-executor";
// IMPORTANT to prefix it with `0x`!
const runtime = "0x" + fs.readFileSync("runtime.wasm").toString("hex");
// returns a `0x` prefixed OpaqueMetadata. It's as well prefixed by a compactInt of its length
const metadata = getMetadataFromRuntime(runtime);