diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index aa8b818..91029a4 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -51,3 +51,15 @@ jobs:
       run: make -C tests/simple run-base
     - name: Build and run wevaled 'simple' test
       run: make -C tests/simple run-wevaled
+
+  test-js:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - uses: actions/setup-node@v4
+      with:
+        node-version: latest
+    - run: npm install
+      working-directory: npm/weval
+    - run: npm test
+      working-directory: npm/weval
diff --git a/npm/weval/index.js b/npm/weval/index.js
index 66f4bee..aff6873 100644
--- a/npm/weval/index.js
+++ b/npm/weval/index.js
@@ -14,7 +14,14 @@ const __dirname = dirname(fileURLToPath(import.meta.url));
 
 const TAG = "v0.3.2";
 
-async function getWeval() {
+/**
+ * Download Weval from GitHub releases
+ *
+ * @param {object} [opts]
+ * @param {string} [opts.downloadDir] - Directory to which the binary should be downloaded
+ * @returns {string} path to the downloaded binary on disk
+ */
+export async function getWeval(opts) {
   const knownPlatforms = {
     "win32 x64 LE": "x86_64-windows",
     "darwin arm64 LE": "aarch64-macos",
@@ -38,7 +45,7 @@ async function getWeval() {
   const assetSuffix = platform == "win32" ? "zip" : "tar.xz";
   const exeSuffix = platform == "win32" ? ".exe" : "";
 
-  const exeDir = join(__dirname, platformName);
+  const exeDir = join(opts && opts.downloadDir ? opts.downloadDir : __dirname, platformName);
   const exe = join(exeDir, `weval${exeSuffix}`);
 
   // If we already have the executable installed, then return it
diff --git a/npm/weval/package.json b/npm/weval/package.json
index 52f73ea..7199ba9 100644
--- a/npm/weval/package.json
+++ b/npm/weval/package.json
@@ -4,6 +4,7 @@
   "description": "The WebAssembly partial evaluator",
   "type": "module",
   "scripts": {
+    "test": "node ./tests/index.mjs",
     "version": "node ./update.js $npm_package_version"
   },
   "dependencies": {
diff --git a/npm/weval/tests/download.mjs b/npm/weval/tests/download.mjs
new file mode 100644
index 0000000..e5f142c
--- /dev/null
+++ b/npm/weval/tests/download.mjs
@@ -0,0 +1,17 @@
+import assert from "node:assert";
+import { test } from "node:test";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { mkdtemp, access } from 'node:fs/promises';
+
+import { getWeval } from "../index.js";
+
+export default async function tests() {
+  test("downloading works", async () => {
+    const downloadDir = await mkdtemp(join(tmpdir(), "weval-dl-"));
+    const wevalPath = await getWeval({ downloadDir });
+    assert(wevalPath);
+    await access(wevalPath);
+    console.log(`weval path: ${wevalPath}`);
+  });
+}
diff --git a/npm/weval/tests/index.mjs b/npm/weval/tests/index.mjs
new file mode 100644
index 0000000..fc6542d
--- /dev/null
+++ b/npm/weval/tests/index.mjs
@@ -0,0 +1,3 @@
+import { default as downloadTests }  from "./download.mjs";
+
+await downloadTests();