# prepin

> An in-place pre-processor for javascript files using C style pre-compile syntax to compose custom builds from npm-packages

Latest version **1.0.3** (published 2019-05-10) · Unlicense license · 0 weekly downloads

## Install

```sh
npm install prepin
pnpm add prepin
yarn add prepin
bun add prepin
```

Provides the command `prepin`.

## Health

**Score 15/100 (F)** — status: abandoned.

Positive: no vulnerabilities.

Warnings: low downloads; no types; no esm support.

Negative: abandoned; low maintenance score.

## Facts

| | |
|---|---|
| Version | 1.0.3 |
| Published | 2019-05-10 |
| First published | 2017-06-10 |
| Weekly downloads | 0 |
| License | Unlicense |
| TypeScript types | none |
| Module format | CommonJS |
| Dependencies | 0 |
| Unpacked size | 15.3 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 0 |
| Author | commenthol |
| Maintainers | commenthol |
| Keywords | builds, custom, inplace, preprocessor |

## Links

- npm: https://www.npmjs.com/package/prepin
- Repository: https://github.com/commenthol/prepin
- Homepage: https://github.com/commenthol/prepin#readme
- Issues: https://github.com/commenthol/prepin/issues
- npm.io page: https://npm.io/package/prepin

## Recent versions

- 1.0.3 (latest) — 2019-05-10
- 1.0.1 — 2017-06-10
- 1.0.0 — 2017-06-10

## README

# prepin

> An in-place pre-processor for javascript files using C style pre-compile
syntax to compose custom builds from npm-packages.

[![NPM version][badge]][repo]

Pre-processors found on [npm][] require a different file for outputting
processed changes. This is not ideal for in-place custom builds on already
published packages. This pre-processors main purpose is to allow reduction of
package size for e.g. single-page apps on not requiring modules based on macros
given at transpile time.

## Syntax

Follows C style pre-compiler syntax but requires `//` right in front to work in
.js files.

```
// #if expression             // e.g. // #if macro == 1
// #if defined(macro)
// #ifdef macro
// #ifndef macro
// #elif expression           // e.g. // #elif macro == 2
// #else
// #endif
// # is a commented line
```

## Example

Let's assume a `example/sample.js` file, which includes a package of large size which is
required for a specific task is not used in a smaller custom build...

The original file:

```js
// #ifndef small
const big = require('./big-package')
// #else
// # let big // define the alternative
// #endif

if (big) {
  // ...
}
```

If processing with `prepin -m small sample.js` you'll get:

```js
// #ifndef small
// # const big = require('./big-package')
// #else
let big // define the alternative
// #endif

if (big) {
  // ...
}
```

## CLI

```
prepin [options] [file]

Options:

  -m macro=1    define macro
  -o <output>   write output to file

Examples:

  cat sample.js | prepin -m small
      reads from stdin and transpiles using macro "small", writes to stdout.

  prepin -m small=1 -m other sample.js
      pre-process with macros small=1, other on sample.js
```

## API

```js
const Prepin = require('prepin')

const opts = {macros: {small: true}, input: 'sample.js', output: 'sample.js'}

new Prepin(opts).proc().catch((e) => console.error(e))
```

## License

[UNLICENSE][]

[badge]: https://badge.fury.io/js/prepin.svg
[repo]: https://www.npmjs.com/package/prepin

[npm]: https://npmjs.org
[UNLICENSE]: http://unlicense.org

---
_Source: https://npm.io/package/prepin · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._