feat: add js-wasm bindings and formalise WASM runtime support (VirusTotal#598)

This PR adds a browser-facing JavaScript package for yara-x and the supporting library changes needed to run it on wasm32-unknown-unknown.

The main library change is a refactor of the internal WASM runtime layer so that non-Wasm targets continue to use wasmtime, while browser builds use a small compatibility shim over the host WebAssembly runtime. The browser-specific runtime code is isolated under lib/src/wasm/runtime/, which keeps the rest of the library largely unchanged and avoids spreading target-specific conditionals across the codebase.

On top of that, this PR adds a new in-tree js-wasm package. It exposes an object-based JavaScript API built around `Compiler`, `Rules`, and `Scanner`, and is packaged using a wasm-pack-based workflow.

Author: niallnsec

.github/workflows/tests.yaml

@@ -178,4 +178,72 @@ jobs:
       - name: Run doc tests
         run: cargo doc --no-deps
         env:
-          RUSTDOCFLAGS: ${{ matrix.rust_flags }}
+          RUSTDOCFLAGS: ${{ matrix.rust_flags }}
+
+  browser-wasm:
+    name: Browser WASM
+    runs-on: ubuntu-latest
+    env:
+      CARGO_TERM_COLOR: always
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683  # v4.2.2
+
+      - name: Install Rust toolchain
+        uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: stable
+          target: wasm32-unknown-unknown
+
+      - name: Install Node.js
+        uses: actions/setup-node@1d0ff469b7ec7b3cb9d8673fde0c81c44821de2a  # v4.2.0
+        with:
+          node-version: 22
+
+      - name: Install Chrome and ChromeDriver
+        id: setup-chrome
+        uses: browser-actions/setup-chrome@v2
+        with:
+          chrome-version: stable
+          install-dependencies: true
+          install-chromedriver: true
+
+      - name: Add ChromeDriver to PATH
+        run: echo "$(dirname '${{ steps.setup-chrome.outputs.chromedriver-path }}')" >> "$GITHUB_PATH"
+
+      - name: Install wasm-pack
+        run: cargo install --locked wasm-pack --version 0.14.0
+
+      - name: Install wasm-bindgen CLI
+        run: cargo install --locked wasm-bindgen-cli --version 0.2.113
+
+      - name: Install terser
+        run: npm install --global terser
+
+      - name: Write webdriver.json
+        run: |
+          cat > js-wasm/webdriver.json <<EOF
+          {
+            "goog:chromeOptions": {
+              "binary": "${{ steps.setup-chrome.outputs.chrome-path }}"
+            }
+          }
+          EOF
+
+      - name: Run Node-targeted Rust tests
+        run: npm --prefix js-wasm run test:wasm-node
+
+      - name: Run headless browser Rust tests
+        run: npm --prefix js-wasm run test:wasm-browser
+        env:
+          CHROMEDRIVER: ${{ steps.setup-chrome.outputs.chromedriver-path }}
+          WASM_BINDGEN_TEST_WEBDRIVER_JSON: ${{ github.workspace }}/js-wasm/webdriver.json
+
+      - name: Build browser package
+        run: npm --prefix js-wasm run build:web
+
+      - name: Run JS integration tests
+        run: npm --prefix js-wasm run test:js
+
+      - name: Validate npm package contents
+        run: npm --prefix js-wasm run pack:dry-run

.gitignore

@@ -1,3 +1,4 @@
+.DS_Store
 .env
 .idea
 .pytest_cache
@@ -6,6 +7,8 @@
 *.profraw
 *.swp
 target
+js-wasm/dist
+js-wasm/pkg
 macros/target
 site/node_modules
 site/public