Removes bundle_js flag from prerender_pages.

This flag served only as a minor optimization for skipping the bundling phase when no client-side JavaScript was expected. It was required before because Rollup would throw a hard error if no entry points were given to be bundled. Now the `js_bundle` rule passes when given no inputs and generates an empty output directory as would be expected. As a result, `bundle_js` is no longer required to avoid errors and the optimization benefits are so trivial as to not be worth the trade off. If a user forgets scripts are disabled for a page and then adds scripts to a component, they may be very confused to find those scripts are not loaded. Requiring a bundle step for client-side JavaScript means this mistake can never be made.

Author: dgp1130

packages/rules_prerender/multi_inject_resources.bzl

@@ -20,8 +20,7 @@ def _multi_inject_resources_impl(ctx):
     args = ctx.actions.args()
     args.add("--input-dir", ctx.file.input_dir.short_path)
     args.add("--config", config.short_path)
-    if ctx.attr.bundles:
-        args.add("--bundles", ctx.file.bundles.short_path)
+    args.add("--bundles", ctx.file.bundles.short_path)
     args.add("--output-dir", output_dir.short_path)
     ctx.actions.run(
         mnemonic = "MultiInjectResources",
@@ -49,7 +48,10 @@ multi_inject_resources = rule(
             mandatory = True,
             allow_single_file = True,
         ),
-        "bundles": attr.label(allow_single_file = True),
+        "bundles": attr.label(
+            mandatory = True,
+            allow_single_file = True,
+        ),
         "scripts": attr.string_list(),
         "styles": attr.label(),
         "_injector": attr.label(

packages/rules_prerender/prerender_pages.bzl

@@ -14,7 +14,6 @@ def prerender_pages(
     scripts = None,
     styles = None,
     resources = None,
-    bundle_js = True,
     testonly = None,
     visibility = None,
     debug_target = None,
@@ -76,8 +75,6 @@ def prerender_pages(
         scripts: Passed through to `prerender_pages_unbundled()`.
         styles: Passed through to `prerender_pages_unbundled()`.
         resources: Passed through to `prerender_pages_unbundled()`.
-        bundle_js: Whether or not to bundle and inject JavaScript files.
-            Defaults to `True`.
         testonly: See https://docs.bazel.build/versions/master/be/common-definitions.html.
         visibility: See https://docs.bazel.build/versions/master/be/common-definitions.html.
         debug_target: The label to check
@@ -100,22 +97,21 @@ def prerender_pages(
         debug_target = debug_target or "//%s:%s" % (native.package_name(), name),
     )
 
+    # Bundle all client-side scripts in a `TreeArtifact` at `%{name}_bundle`.
     bundle = "%s_bundle" % name
-    if bundle_js:
-        # Bundle all client-side scripts in a `TreeArtifact` at `%{name}_bundle`.
-        js_bundle(
-            name = bundle,
-            entry_points = ":%s_scripts_entries" % prerender_name,
-            testonly = testonly,
-            deps = [":%s_scripts" % prerender_name],
-        )
+    js_bundle(
+        name = bundle,
+        entry_points = ":%s_scripts_entries" % prerender_name,
+        testonly = testonly,
+        deps = [":%s_scripts" % prerender_name],
+    )
 
     # Inject bundled JS and CSS into the HTML.
     injected_dir = "%s_injected" % name
     multi_inject_resources(
         name = injected_dir,
         input_dir = ":%s" % prerender_name,
-        bundles = ":%s" % bundle if bundle_js else None,
+        bundles = ":%s" % bundle,
         styles = ":%s_styles" % prerender_name,
         testonly = testonly,
     )

packages/rules_prerender/rollup.config.mts

@@ -12,9 +12,7 @@ export default {
         if (warning.code === 'EMPTY_BUNDLE') {
             // Give a better suggestion when no JavaScript is generated.
             console.warn('Generated an empty JavaScript bundle, do you have'
-                + ' any JavaScript? If not, consider setting'
-                + ' `bundle_js = False` on your `prerender_pages()` to skip'
-                + ' this step.\n\n' + warning.message);
+                + ' any JavaScript?\n\n' + warning.message);
             return;
         }