initial commit, add bitget rest api and websockets connector

src/util/node-support.ts

@@ -0,0 +1,23 @@
+import { createHmac } from 'crypto';
+
+/** This is async because the browser version uses a promise (browser-support) */
+export async function signMessage(
+  message: string,
+  secret: string,
+  method: 'hex' | 'base64'
+): Promise<string> {
+  const hmac = createHmac('sha256', secret).update(message);
+
+  switch (method) {
+    case 'hex': {
+      return hmac.digest('hex');
+    }
+    case 'base64': {
+      return hmac.digest().toString('base64');
+    }
+    default: {
+      ((x: never) => {})(method);
+      throw new Error(`Unhandled sign method: ${method}`);
+    }
+  }
+}