Bundler

A Go tool that bundles TypeScript scripts into a single webview.js for each platform (Android and Xcode). Replaces the shell-based esbuild tasks with a cross-platform binary that works on macOS, Linux, and Windows.

Requirements

Go 1.26 or newer (only for compilation. dist directory contains binaries).
go-task (optional, only for the tasks below).
esbuild. (provided by task esbuild.install)

Usage

From tools/bundler/src:

go run . --platform android \
  --common lib/common/scripts \
  --platform-dir lib/android/scripts \
  --esbuild tools/vendor/esbuild/dist/esbuild-$(go env GOOS)-$(go env GOARCH) \
  --tsconfig lib/common/config/bundler.json \
  --output build/android/scripts/webview.js

Flags

Flag Required Description

Flag	Required	Description
`--platform`	Yes	Target platform: `android` or `xcode`.
`--common`	Yes	Path to common scripts directory (`lib/common/scripts`).
`--platform-dir`	Yes	Path to platform-specific scripts (`lib/android/scripts` or `lib/xcode/scripts`).
`--esbuild`	Yes	Path to the vendored esbuild binary.
`--output`	Yes	Final output path for the bundled JS file.
`--tsconfig`	No	Path to TypeScript config for the bundler. Default: `lib/common/config/bundler.json`.
`--target`	No	esbuild target. Default: `safari11`.
`--banner`	No	Banner comment prepended to output. Default: auto-generated comment.

--platform

Yes

Target platform: android or xcode.

--common

Yes

Path to common scripts directory (lib/common/scripts).

--platform-dir

Yes

Path to platform-specific scripts (lib/android/scripts or lib/xcode/scripts).

--esbuild

Yes

Path to the vendored esbuild binary.

--output

Yes

Final output path for the bundled JS file.

--tsconfig

Path to TypeScript config for the bundler. Default: lib/common/config/bundler.json.

--target

esbuild target. Default: safari11.

--banner

Banner comment prepended to output. Default: auto-generated comment.

How it works

Creates a staging directory at build/<platform>/js and build/<platform>/scripts.
Copies common scripts into build/<platform>/scripts/.
Copies platform-specific scripts on top (overrides common files with the same name).
Invokes the vendored esbuild binary via os/exec to bundle main.ts into build/<platform>/js/main.js.
Moves the result to --output path.
Cleans up staging directories.

All file operations use Go’s os and filepath packages, which are cross-platform. No shell commands are used.

Script structure

lib/common/scripts/       # shared TypeScript, included in both platforms
lib/android/scripts/      # Android overrides (copied over common)
lib/xcode/scripts/        # Xcode overrides (copied over common)

TypeScript config for the bundler: lib/common/config/bundler.json.

Output

Xcode: build/xcode/scripts/webview.js
Android: build/android/scripts/webview.js

A banner comment is prepended to mark the file as auto-generated.

Tasks

From the repository root:

task bundler (bn): bundle scripts for both Xcode and Android.
task bundler.xcode (bx): bundle scripts for Xcode only.
task bundler.android (ba): bundle scripts for Android only.
task bundler.build (bb): build the tools/bundler binary.

From tools/bundler/src:

task build (b): cross-compile binaries into ../dist/ for macOS (amd64/arm64), Linux (amd64) and Windows (amd64).
task test (t): run the test suite.

Release binaries

dist contains prebuilt binaries for each platform, named bundler-<os>-<arch> (Windows uses .exe).

Bundle flags (esbuild)

The tool passes these flags to esbuild:

--bundle — resolves imports and produces a single output file.
--target=safari11 — output compatible with Safari 11+ (WKWebView).
--analyze — prints a bundle size breakdown.
--tsconfig — uses the specified TypeScript config for module resolution.