--footer esbuild & rollup style! (#14396)

Co-authored-by: Jarred Sumner <jarred@jarredsumner.com>

docs/bundler/index.md

@@ -1092,7 +1092,7 @@ $ bun build ./index.tsx --outdir ./out --loader .png:dataurl --loader .txt:file
 
 ### `banner`
 
-A banner to be added to the final bundle, this can be a directive like "use client" for react or a comment block such as a license for the code. 
+A banner to be added to the final bundle, this can be a directive like "use client" for react or a comment block such as a license for the code.
 
 {% codetabs %}
 
@@ -1108,11 +1108,29 @@ await Bun.build({
 $ bun build ./index.tsx --outdir ./out --banner "\"use client\";"
 ```
 
+### `footer`
+
+A footer to be added to the final bundle, this can be something like a comment block for a license or just a fun easter egg.
+
+{% codetabs %}
+
+```ts#JavaScript
+await Bun.build({
+  entrypoints: ['./index.tsx'],
+  outdir: './out',
+  footer: '// built with love in SF'
+})
+```
+
+```bash#CLI
+$ bun build ./index.tsx --outdir ./out --footer="// built with love in SF"
+```
+
 {% /codetabs %}
 
 ### `experimentalCss`
 
-Whether to enable *experimental* support for bundling CSS files. Defaults to `false`.
+Whether to enable _experimental_ support for bundling CSS files. Defaults to `false`.
 
 This supports bundling CSS files imported from JS, as well as CSS entrypoints.
 

docs/bundler/vs-esbuild.md

@@ -159,6 +159,12 @@ In Bun's CLI, simple boolean flags like `--minify` do not accept an argument. Ot
 
 ---
 
+- `--footer`
+- `--footer`
+- Only applies to js bundles
+
+---
+
 - `--certfile`
 - n/a
 - Not applicable
@@ -195,12 +201,6 @@ In Bun's CLI, simple boolean flags like `--minify` do not accept an argument. Ot
 
 ---
 
-- `--footer`
-- n/a
-- Not supported
-
----
-
 - `--global-name`
 - n/a
 - Not applicable, Bun does not support `iife` output at this time

packages/bun-types/bun.d.ts

@@ -1599,6 +1599,12 @@ declare module "bun" {
      * Add a banner to the bundled code such as "use client";
      */
     banner?: string;
+    /**
+     * Add a footer to the bundled code such as a comment block like
+     *
+     * `// made with bun!`
+     */
+    footer?: string;
 
     /**
      * **Experimental**

src/bun.js/api/JSBundler.zig

@@ -73,6 +73,7 @@ pub const JSBundler = struct {
         format: options.Format = .esm,
         bytecode: bool = false,
         banner: OwnedString = OwnedString.initEmpty(bun.default_allocator),
+        footer: OwnedString = OwnedString.initEmpty(bun.default_allocator),
         experimental_css: bool = false,
 
         pub const List = bun.StringArrayHashMapUnmanaged(Config);
@@ -190,6 +191,12 @@ pub const JSBundler = struct {
                 try this.banner.appendSliceExact(slice.slice());
             }
 
+
+            if (try config.getOptional(globalThis, "footer", ZigString.Slice)) |slice| {
+                defer slice.deinit();
+                try this.footer.appendSliceExact(slice.slice());
+            }
+
             if (config.getTruthy(globalThis, "sourcemap")) |source_map_js| {
                 if (bun.FeatureFlags.breaking_changes_1_2 and config.isBoolean()) {
                     if (source_map_js == .true) {

src/bundler/bundle_v2.zig

@@ -876,6 +876,7 @@ pub const BundleV2 = struct {
         this.linker.options.ignore_dce_annotations = bundler.options.ignore_dce_annotations;
 
         this.linker.options.banner = bundler.options.banner;
+        this.linker.options.footer = bundler.options.footer;
 
         this.linker.options.experimental_css = bundler.options.experimental_css;
 
@@ -1478,6 +1479,7 @@ pub const BundleV2 = struct {
             bundler.options.ignore_dce_annotations = config.ignore_dce_annotations;
             bundler.options.experimental_css = config.experimental_css;
             bundler.options.banner = config.banner.toOwnedSlice();
+            bundler.options.footer = config.footer.toOwnedSlice();
 
             bundler.configureLinker();
             try bundler.configureDefines();
@@ -4602,6 +4604,7 @@ pub const LinkerContext = struct {
         minify_syntax: bool = false,
         minify_identifiers: bool = false,
         banner: []const u8 = "",
+        footer: []const u8 = "",
         experimental_css: bool = false,
         source_maps: options.SourceMapOption = .none,
         target: options.Target = .browser,
@@ -8977,7 +8980,16 @@ pub const LinkerContext = struct {
         j.ensureNewlineAtEnd();
         // TODO: maybeAppendLegalComments
 
-        // TODO: footer
+        if (c.options.footer.len > 0) {
+            if (newline_before_comment) {
+                j.pushStatic("\n");
+                line_offset.advance("\n");
+            }
+            j.pushStatic(ctx.c.options.footer);
+            line_offset.advance(ctx.c.options.footer);
+            j.pushStatic("\n");
+            line_offset.advance("\n");
+        }
 
         chunk.intermediate_output = c.breakOutputIntoPieces(
             worker.allocator,

src/cli.zig

@@ -263,6 +263,7 @@ pub const Arguments = struct {
         clap.parseParam("--outfile <STR>                  Write to a file") catch unreachable,
         clap.parseParam("--sourcemap <STR>?               Build with sourcemaps - 'linked', 'inline', 'external', or 'none'") catch unreachable,
         clap.parseParam("--banner <STR>                   Add a banner to the bundled output such as \"use client\"; for a bundle being used with RSCs") catch unreachable,
+        clap.parseParam("--footer <STR>                   Add a footer to the bundled output such as // built with bun!") catch unreachable,
         clap.parseParam("--format <STR>                   Specifies the module format to build to. Only \"esm\" is supported.") catch unreachable,
         clap.parseParam("--root <STR>                     Root directory used for multiple entry points") catch unreachable,
         clap.parseParam("--splitting                      Enable code splitting") catch unreachable,
@@ -783,6 +784,10 @@ pub const Arguments = struct {
                 ctx.bundler_options.banner = banner;
             }
 
+            if (args.option("--footer")) |footer| {
+                ctx.bundler_options.footer = footer;
+            }
+
             const experimental_css = args.flag("--experimental-css");
             ctx.bundler_options.experimental_css = experimental_css;
 
@@ -1408,6 +1413,7 @@ pub const Command = struct {
             output_format: options.Format = .esm,
             bytecode: bool = false,
             banner: []const u8 = "",
+            footer: []const u8 = "",
             experimental_css: bool = false,
         };
 

src/cli/build_command.zig

@@ -98,6 +98,8 @@ pub const BuildCommand = struct {
         this_bundler.options.ignore_dce_annotations = ctx.bundler_options.ignore_dce_annotations;
 
         this_bundler.options.banner = ctx.bundler_options.banner;
+        this_bundler.options.footer = ctx.bundler_options.footer;
+
         this_bundler.options.experimental_css = ctx.bundler_options.experimental_css;
 
         this_bundler.options.output_dir = ctx.bundler_options.outdir;

test/bundler/bundler_footer.test.ts

@@ -0,0 +1,29 @@
+import { describe } from "bun:test";
+import { itBundled } from "./expectBundled";
+
+describe("bundler", () => {
+  itBundled("footer/CommentFooter", {
+    footer: "// developed with love in SF",
+    files: {
+      "/a.js": `console.log("Hello, world!")`,
+    },
+    onAfterBundle(api) {
+      api.expectFile("out.js").toEndWith('// developed with love in SF"\n');
+    },
+  });
+  itBundled("footer/MultilineFooter", {
+    footer: `/**
+ * This is copyright of [...] ${new Date().getFullYear()}
+ * do not redistribute without consent of [...]
+*/`,
+    files: {
+      "index.js": `console.log("Hello, world!")`,
+    },
+    onAfterBundle(api) {
+      api.expectFile("out.js").toEndWith(`/**
+ * This is copyright of [...] ${new Date().getFullYear()}
+ * do not redistribute without consent of [...]
+*/\"\n`);
+    },
+  });
+});

test/bundler/expectBundled.ts

@@ -146,6 +146,7 @@ export interface BundlerTestInput {
   alias?: Record<string, string>;
   assetNaming?: string;
   banner?: string;
+  footer?: string;
   define?: Record<string, string | number>;
 
   /** Use for resolve custom conditions */
@@ -416,6 +417,7 @@ function expectBundled(
     external,
     packages,
     files,
+    footer,
     format,
     globalName,
     inject,
@@ -666,6 +668,7 @@ function expectBundled(
               serverComponents && "--server-components",
               outbase && `--root=${outbase}`,
               banner && `--banner="${banner}"`, // TODO: --banner-css=*
+              footer && `--footer="${footer}"`,
               ignoreDCEAnnotations && `--ignore-dce-annotations`,
               emitDCEAnnotations && `--emit-dce-annotations`,
               // inject && inject.map(x => ["--inject", path.join(root, x)]),
@@ -710,6 +713,7 @@ function expectBundled(
               metafile && `--metafile=${metafile}`,
               sourceMap && `--sourcemap=${sourceMap}`,
               banner && `--banner:js=${banner}`,
+              footer && `--footer:js=${footer}`,
               legalComments && `--legal-comments=${legalComments}`,
               ignoreDCEAnnotations && `--ignore-annotations`,
               splitting && `--splitting`,