Add infrastructure to build and publish as wasm32 (#3840)

Co-authored-by: Ingvar Stepanyan <me@rreverser.com>

npm/from-github-release.js

@@ -38,7 +38,8 @@ limitations under the License.
 `;
 
 workspaces.map(async platform => {
-  const url = `https://github.com/lovell/sharp/releases/download/v${version}/sharp-v${version}-napi-v9-${platform}.tar.gz`;
+  const prebuildPlatform = platform === 'wasm32' ? 'emscripten-wasm32' : platform;
+  const url = `https://github.com/lovell/sharp/releases/download/v${version}/sharp-v${version}-napi-v9-${prebuildPlatform}.tar.gz`;
   const dir = path.join(__dirname, platform);
   const response = await fetch(url);
   if (!response.ok) {
@@ -58,8 +59,8 @@ workspaces.map(async platform => {
   await writeFile(path.join(dir, 'README.md'), `# \`${name}\`\n\n${description}.\n${licensing}`);
   // Copy Apache-2.0 LICENSE
   await copyFile(path.join(__dirname, '..', 'LICENSE'), path.join(dir, 'LICENSE'));
-  // Copy Windows-specific files
-  if (platform.startsWith('win32-')) {
+  // Copy files for packages without an explicit sharp-libvips dependency (Windows, wasm)
+  if (platform.startsWith('win') || platform.startsWith('wasm')) {
     const sharpLibvipsDir = path.join(require(`@img/sharp-libvips-${platform}/lib`), '..');
     // Copy versions.json
     await copyFile(path.join(sharpLibvipsDir, 'versions.json'), path.join(dir, 'versions.json'));

npm/package.json

@@ -11,6 +11,7 @@
     "linux-x64",
     "linuxmusl-arm64",
     "linuxmusl-x64",
+    "wasm32",
     "win32-ia32",
     "win32-x64"
   ]

npm/wasm32/package.json

@@ -0,0 +1,42 @@
+{
+  "name": "@img/sharp-wasm32",
+  "version": "0.33.0-alpha.10",
+  "description": "Prebuilt sharp for use with wasm32",
+  "author": "Lovell Fuller <npm@lovell.info>",
+  "homepage": "https://sharp.pixelplumbing.com",
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/lovell/sharp.git",
+    "directory": "npm/wasm32"
+  },
+  "license": "Apache-2.0 AND LGPL-3.0-or-later AND MIT",
+  "funding": {
+    "url": "https://opencollective.com/libvips"
+  },
+  "preferUnplugged": true,
+  "files": [
+    "lib",
+    "versions.json"
+  ],
+  "publishConfig": {
+    "access": "public"
+  },
+  "type": "commonjs",
+  "exports": {
+    "./sharp.node": "./lib/sharp-wasm32.node.js",
+    "./package": "./package.json",
+    "./versions": "./versions.json"
+  },
+  "engines": {
+    "node": "^18.17.0 || ^20.3.0 || >=21.0.0",
+    "npm": ">=9.6.5",
+    "yarn": ">=3.2.0",
+    "pnpm": ">=7.1.0"
+  },
+  "dependencies": {
+    "@emnapi/runtime": "^0.43.1"
+  },
+  "cpu": [
+    "wasm32"
+  ]
+}