source: frontend/node_modules/rollup-plugin-terser/README.md

# rollup-plugin-terser [![Travis Build Status][travis-img]][travis]

[travis-img]: https://travis-ci.org/TrySound/rollup-plugin-terser.svg
[travis]: https://travis-ci.org/TrySound/rollup-plugin-terser

[Rollup](https://github.com/rollup/rollup) plugin to minify generated es bundle. Uses [terser](https://github.com/fabiosantoscode/terser) under the hood.

## Install

```sh
yarn add rollup-plugin-terser --dev
# Or with npm:
npm i rollup-plugin-terser --save-dev
```

_Note: this package requires rollup@0.66 and higher (including rollup@2.0.0)_

## Usage

```js
import { rollup } from "rollup";
import { terser } from "rollup-plugin-terser";

rollup({
  input: "main.js",
  plugins: [terser()],
});
```

## Why named export?

1. Module is a namespace. Default export often leads to function/component per file dogma and makes code less maintainable.
2. Interop with commonjs is broken in many cases or hard to maintain.
3. Show me any good language with default exports. It's historical javascriptism.

## Options

> ⚠️ **Caveat:** any function used in options object cannot rely on its surrounding scope, since it is executed in an isolated context.

```js
terser(options);
```

`options` - [terser API options](https://github.com/fabiosantoscode/terser#minify-options)

Note: some terser options are set by the plugin automatically:

- `module: true` is set when `format` is `esm` or `es`
- `toplevel: true` is set when `format` is `cjs`

`options.numWorkers: number`

Amount of workers to spawn. Defaults to the number of CPUs minus 1.

## Examples

### Using as output plugin

```js
// rollup.config.js
import { terser } from "rollup-plugin-terser";

export default {
  input: "index.js",
  output: [
    { file: "lib.js", format: "cjs" },
    { file: "lib.min.js", format: "cjs", plugins: [terser()] },
    { file: "lib.esm.js", format: "esm" },
  ],
};
```

### Comments

If you'd like to preserve comments (for licensing for example), then you can specify a function to do this like so:

```js
terser({
  output: {
    comments: function (node, comment) {
      var text = comment.value;
      var type = comment.type;
      if (type == "comment2") {
        // multiline comment
        return /@preserve|@license|@cc_on/i.test(text);
      }
    },
  },
});
```

Alternatively, you can also choose to keep all comments (e.g. if a licensing header has already been prepended by a previous rollup plugin):

```js
terser({
  output: {
    comments: "all",
  },
});
```

See [Terser documentation](https://github.com/fabiosantoscode/terser#terser) for further reference.

# License

MIT © [Bogdan Chadkin](mailto:trysound@yandex.ru)