allow to pass custom headers to http-transport in niljs

niljs/src/rpc/rpcClient.test.ts

@@ -8,3 +8,21 @@ test("creates a new RPC client with the correct endpoint", () => {
 
   expect(actualClient).not.toBeUndefined();
 });
+
+test("creates a new RPC client with the correct endpoint and headers", () => {
+  const actualClient = createRPCClient(endpoint, {
+    headers: {
+      "My-header": "my-value",
+    },
+  });
+
+  expect(actualClient).not.toBeUndefined();
+});
+
+test("throws an error when the headers are invalid (helps in JavaScript)", () => {
+  const headers = {
+    "Invalid-header": 333,
+  } as unknown as Record<string, string>;
+
+  expect(() => createRPCClient(endpoint, { headers })).toThrow();
+});

niljs/src/rpc/rpcClient.ts

@@ -1,12 +1,14 @@
 import { Client, HTTPTransport, RequestManager } from "@open-rpc/client-js";
 import fetch from "isomorphic-fetch";
+import { isValidHttpHeaders } from "../utils/rpc.js";
 import { version } from "../version.js";
 
 /**
  * The options for the RPC client.
  */
 type RPCClientOptions = {
   signal?: AbortSignal;
+  headers?: Record<string, string>;
 };
 
 /**
@@ -15,14 +17,17 @@ type RPCClientOptions = {
  * HTTP is currently the only supported transport.
  * @example const client = createRPCClient(RPC_ENDPOINT);
  */
-const createRPCClient = (endpoint: string, { signal }: RPCClientOptions = {}) => {
+const createRPCClient = (endpoint: string, { signal, headers = {} }: RPCClientOptions = {}) => {
   const fetcher: typeof fetch = (url, options) => {
     return fetch(url, { ...options, signal });
   };
 
+  isValidHttpHeaders(headers);
+
   const transport = new HTTPTransport(endpoint, {
     headers: {
       "Client-Version": version,
+      ...headers,
     },
     fetcher,
   });

niljs/src/transport/HttpTransport.ts

@@ -33,8 +33,8 @@ class HttpTransport implements ITransport {
    * @constructor
    * @param {IHttpTransportConfig} config The transport config. See {@link IHttpTransportConfig}.
    */
-  constructor({ endpoint, signal, timeout = 20000 }: IHttpTransportConfig) {
-    this.rpcClient = createRPCClient(endpoint, { signal });
+  constructor({ endpoint, signal, timeout = 20000, headers }: IHttpTransportConfig) {
+    this.rpcClient = createRPCClient(endpoint, { signal, headers });
     this.timeout = timeout;
   }
 

niljs/src/transport/types/IHttpTransportConfig.ts

@@ -21,6 +21,12 @@ type IHttpTransportConfig = {
    * @default undefined
    */
   signal?: AbortSignal;
+  /**
+   * The headers to be sent with the request.
+   * @example { 'My-header': 'my-value' }
+   * @default {}
+   */
+  headers?: Record<string, string>;
 };
 
 export type { IHttpTransportConfig };

niljs/src/utils/rpc.ts

@@ -0,0 +1,18 @@
+function isValidHttpHeaders(headers: unknown) {
+  if (headers === null || typeof headers !== "object" || Array.isArray(headers)) {
+    throw new Error("Invalid headers provided to the RPC client.");
+  }
+
+  const isValidObj = Object.entries(headers).every(
+    ([key, value]) =>
+      typeof key === "string" &&
+      (typeof value === "string" ||
+        (Array.isArray(value) && value.every((v) => typeof v === "string"))),
+  );
+
+  if (!isValidObj) {
+    throw new Error("Invalid http headers provided to the RPC client.");
+  }
+}
+
+export { isValidHttpHeaders };