Bundle Typescript without transpiling?

[stevefan1999-personal]

I want to integrate rollup with TypescriptToLua which does not support JS imports yet, so I have to use a bundler to pack Typescript in.

However it uses Typescript types to do optimization and I wonder if that is possible for rollup to not transpile the Typescript, and instead just process the static ES modules import/export. Don't strip types.

For node_modules that have corresponding Typescript source, include them into the bundle as much as possible. That way we can ensure highest level of tstl compatibility

[potatohoney-p]

If you mean the TypeScriptToLua compiler, you can keep the TypeScript files separate until that compiler processes them, and bundle its Lua output rather than producing a type-preserving .ts bundle with Rollup:

{
  "compilerOptions": {
    "target": "ESNext",
    "strict": true,
    "rootDir": "src",
    "outDir": "dist",
    "noEmitOnError": true
  },
  "include": ["src/**/*.ts"],
  "tstl": {
    "luaTarget": "5.4",
    "luaBundle": "bundle.lua",
    "luaBundleEntry": "src/main.ts"
  }
}

Run tstl -p tsconfig.json. For example:

// src/math.ts
export function double(value: number): number { return value * 2; }

// src/main.ts
import { double } from './math';
export const result: number = double(21);

I checked this with typescript-to-lua@1.37.1 / TypeScript 6.0.2: it emitted one dist/bundle.lua containing both modules. Changing the call to double("invalid") failed with TS2345, so the typed source reaches the compiler rather than passing through a JavaScript/type-erasure stage first. This verifies compilation and emitted module inclusion, not Lua runtime execution.

The options are documented here. Rollup's normal TypeScript-plugin pipeline instead transforms the input into JavaScript for Rollup; it isn't a type-preserving TypeScript source bundler. Removing that transform is not sufficient either: a bare Rollup 3.7.5 build of the typed entry above fails parsing the type annotation.

There is an important limit for the dependency part of your question: TypeScriptToLua's module documentation explicitly says it cannot import .ts/.tsx sources from a node_modules library. Its supported Lua-library route uses Lua code plus TypeScript declarations. The configuration above therefore solves bundling your project modules, not automatic compatibility with arbitrary npm packages just because they ship TypeScript sources.