Remove btoa (#192)

The `btoa` function must now be passed in as a middleware option. This
lets us remove an additional dependency, and makes this package less
dependent upon Node.js or browser specific APIs.

package.json

@@ -31,7 +31,6 @@
     "@metamask/eth-sig-util": "^5.0.0",
     "@metamask/safe-event-emitter": "^2.0.0",
     "@metamask/utils": "^3.0.3",
-    "btoa": "^1.2.1",
     "clone": "^2.1.1",
     "eth-block-tracker": "^6.1.0",
     "eth-rpc-errors": "^4.0.3",

src/fetch.test.ts

@@ -1,5 +1,17 @@
 import { createFetchConfigFromReq } from '.';
 
+/**
+ * Generate a base64-encoded string from a binary string. This should be equivalent to
+ * `window.btoa`.
+ *
+ * @param stringToEncode - The string to encode.
+ * @returns The base64-encoded string.
+ */
+// eslint-disable-next-line @typescript-eslint/no-shadow
+function btoa(stringToEncode: string) {
+  return Buffer.from(stringToEncode).toString('base64');
+}
+
 describe('fetch', () => {
   it('should create a fetch config from a request', async () => {
     const req = {
@@ -9,7 +21,11 @@ describe('fetch', () => {
       params: ['0x482103', true],
     };
     const rpcUrl = 'http://www.xyz.io/rabbit:3456?id=100';
-    const { fetchUrl, fetchParams } = createFetchConfigFromReq({ req, rpcUrl });
+    const { fetchUrl, fetchParams } = createFetchConfigFromReq({
+      btoa,
+      req,
+      rpcUrl,
+    });
     expect(fetchUrl).toStrictEqual(rpcUrl);
     expect(fetchParams).toStrictEqual({
       method: 'POST',
@@ -32,6 +48,7 @@ describe('fetch', () => {
     const rpcUrl = 'http://www.xyz.io/rabbit:3456?id=100';
     const originHttpHeaderKey = 'x-dapp-origin';
     const { fetchUrl, fetchParams } = createFetchConfigFromReq({
+      btoa,
       req: requestWithOrigin,
       rpcUrl,
       originHttpHeaderKey,

src/fetch.ts

@@ -6,10 +6,6 @@ import {
 import { EthereumRpcError, ethErrors } from 'eth-rpc-errors';
 import type { Block } from './types';
 
-/* eslint-disable @typescript-eslint/no-require-imports,@typescript-eslint/no-shadow */
-const btoa = global.btoa || require('btoa');
-/* eslint-enable @typescript-eslint/no-require-imports,@typescript-eslint/no-shadow */
-
 const RETRIABLE_ERRORS: string[] = [
   // ignore server overload errors
   'Gateway timeout',
@@ -38,24 +34,29 @@ interface FetchConfig {
  * Create middleware for sending a JSON-RPC request to the given RPC URL.
  *
  * @param options - Options
+ * @param options.btoa - Generates a base64-encoded string from a binary string.
  * @param options.fetch - The `fetch` function; expected to be equivalent to `window.fetch`.
  * @param options.rpcUrl - The URL to send the request to.
  * @param options.originHttpHeaderKey - If provider, the origin field for each JSON-RPC request
  * will be attached to each outgoing fetch request under this header.
  * @returns The fetch middleware.
  */
 export function createFetchMiddleware({
+  // eslint-disable-next-line @typescript-eslint/no-shadow
+  btoa,
   // eslint-disable-next-line @typescript-eslint/no-shadow
   fetch,
   rpcUrl,
   originHttpHeaderKey,
 }: {
+  btoa: (stringToEncode: string) => string;
   fetch: typeof global.fetch;
   rpcUrl: string;
   originHttpHeaderKey?: string;
 }): JsonRpcMiddleware<unknown, unknown> {
   return createAsyncMiddleware(async (req, res, _next) => {
     const { fetchUrl, fetchParams } = createFetchConfigFromReq({
+      btoa,
       req,
       rpcUrl,
       originHttpHeaderKey,
@@ -136,11 +137,24 @@ function parseResponse(fetchRes: Response, body: Record<string, Block>): Block {
   return body.result;
 }
 
+/**
+ * Generate `fetch` configuration for sending the given request to an RPC API.
+ *
+ * @param options - Options
+ * @param options.btoa - Generates a base64-encoded string from a binary string.
+ * @param options.rpcUrl - The URL to send the request to.
+ * @param options.originHttpHeaderKey - If provider, the origin field for each JSON-RPC request
+ * will be attached to each outgoing fetch request under this header.
+ * @returns The fetch middleware.
+ */
 export function createFetchConfigFromReq({
+  // eslint-disable-next-line @typescript-eslint/no-shadow
+  btoa,
   req,
   rpcUrl,
   originHttpHeaderKey,
 }: {
+  btoa: (stringToEncode: string) => string;
   rpcUrl: string;
   originHttpHeaderKey?: string;
   req: PayloadWithOrigin;

yarn.lock

@@ -867,7 +867,6 @@ __metadata:
     "@types/pify": ^3.0.2
     "@typescript-eslint/eslint-plugin": ^4.21.0
     "@typescript-eslint/parser": ^4.21.0
-    btoa: ^1.2.1
     clone: ^2.1.1
     eslint: ^7.14.0
     eslint-config-prettier: ^8.1.0
@@ -1883,15 +1882,6 @@ __metadata:
   languageName: node
   linkType: hard
 
-"btoa@npm:^1.2.1":
-  version: 1.2.1
-  resolution: "btoa@npm:1.2.1"
-  bin:
-    btoa: bin/btoa.js
-  checksum: afbf004fb1b1d530e053ffa66ef5bd3878b101c59d808ac947fcff96810b4452abba2b54be687adadea2ba9efc7af48b04228742789bf824ef93f103767e690c
-  languageName: node
-  linkType: hard
-
 "buffer-from@npm:^1.0.0":
   version: 1.1.2
   resolution: "buffer-from@npm:1.1.2"