add support for "browser" object entrypoints (#222)

src/index.ts

@@ -207,7 +207,22 @@ function resolveWebDependency(dep: string, isExplicit: boolean): DependencyLoc {
     );
   }
   let foundEntrypoint: string =
-    depManifest['browser:module'] || depManifest.module || depManifest.browser;
+    depManifest['browser:module'] ||
+    depManifest.module ||
+    depManifest['main:esnext'] ||
+    depManifest.browser;
+  // Some packages define "browser" as an object. We'll do our best to find the
+  // right entrypoint in an entrypoint object, or fail otherwise.
+  // See: https://github.com/defunctzombie/package-browser-field-spec
+  if (typeof foundEntrypoint === 'object') {
+    foundEntrypoint =
+      foundEntrypoint[dep] ||
+      foundEntrypoint['./index.js'] ||
+      foundEntrypoint['./index'] ||
+      foundEntrypoint['./'] ||
+      foundEntrypoint['.'] ||
+      foundEntrypoint;
+  }
   // If the package was a part of the explicit whitelist, fallback to it's main CJS entrypoint.
   if (!foundEntrypoint && isExplicit) {
     foundEntrypoint = depManifest.main || 'index.js';
@@ -233,6 +248,9 @@ function resolveWebDependency(dep: string, isExplicit: boolean): DependencyLoc {
       ),
     );
   }
+  if (typeof foundEntrypoint !== 'string') {
+    throw new Error(`"${dep}" has unexpected entrypoint: ${JSON.stringify(foundEntrypoint)}.`);
+  }
   return {
     type: 'JS',
     loc: path.join(depManifestLoc, '..', foundEntrypoint),

test/integration/dep-entrypoint-object/expected-install/import-map.json

@@ -0,0 +1,5 @@
+{
+  "imports": {
+    "mock-test-package": "./mock-test-package.js"
+  }
+}

test/integration/dep-entrypoint-object/expected-output.txt

@@ -0,0 +1,2 @@
+- snowpack installing...
+✔ snowpack installed: mock-test-package.

test/integration/dep-entrypoint-object/package.json

@@ -0,0 +1,9 @@
+{
+  "description": "Test that the --optimize flag overrides the config",
+  "scripts": {
+    "TEST": "node ../../../pkg/dist-node/index.bin.js --optimize"
+  },
+  "dependencies": {
+    "mock-test-package": "^1.2.3"
+  }
+}