TypeScript Function Inliner
TypeScript transformation that inlines calls to small functions. âš¡ï¸
## Explanation
Many projects choose to extract common shared logic into small helper functions.
TypeScript projects often use small [user-defined type guards](https://www.typescriptlang.org/docs/handbook/2/narrowing.html#using-type-predicates) to inform type narrowing.
Unfortunately, the overhead of extracting logic into functions can hurt application performance before JIT optimizers fully kick in.[^1]
This TypeScript transformation plugin detects calls to small one-line functions and inlines them in the output JavaScript.
The resultant code will function the same regardless of the transformation.
### Example
Given the following function:
```ts
export function isNotFalsy(value: unknown) {
return !!value;
}
```
Before:
```ts
isNotFalsy("Hello!");
```
After:
```ts
!!"Hello!";
```
> Note: this transformer does not remove the original function declarations.
> Use a separate tool after the transform, such as [Terser](https://github.com/terser/terser), if you'd like to configure that.
## Usage
```shell
npm i ts-function-inliner
```
Per [github.com/Microsoft/TypeScript/issues/14419](https://github.com/Microsoft/TypeScript/issues/14419), TSConfig plugins don't support transformers.
However, you can use this in other pipelines.
### Usage with Gulp
Specify it as a custom transformer with [gulp-typescript](https://github.com/ivogabe/gulp-typescript):
```ts
import gulp from "gulp";
import ts from "gulp-typescript";
import { transformerProgram } from "ts-function-inliner";
gulp.task("typescript", function () {
gulp
.src("src/**/*.ts")
.pipe(
ts({
getCustomTransformers: (program) => ({
before: [transformerProgram(program)],
}),
}),
)
.pipe(gulp.dest("lib"));
});
```
## Development
See [`.github/CONTRIBUTING.md`](./.github/CONTRIBUTING.md).
Thanks! 💖
## Contributors
[^1]: See [Microsoft/TypeScript: Added some Type type predicates internally #50010](https://github.com/microsoft/TypeScript/pull/50010), which caused a 1-2% performance hit in TypeScript.
> 💙 This package was templated with [create-typescript-app](https://github.com/JoshuaKGoldberg/create-typescript-app).
