rollup-plugin-consts
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Import build time constants with Rollup
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# rollup-plugin-consts
[](https://www.npmjs.com/package/rollup-plugin-consts)
Import build time constants with Rollup.
## Installation
```bash
npm install --save-dev rollup-plugin-consts
```
## Usage
rollup-plugin-consts let you use constants that are replaced at build time, such
as inlining your `NODE_ENV`. Unlike similar plugins such as
[rollup-plugin-replace](https://github.com/rollup/rollup-plugin-replace),
rollup-plugin-consts doesn't magically replace strings in your script. Instead,
you import them like a module.
```js
// script.js
import environment from 'consts:environment';
if (environment === 'production') {
// Production only code ...
} else {
// Development only code ...
}
```
All consts modules have the prefix `consts:` followed by the name of the
constant, such as `environment` or `testing`. Rollup can reduce simple `if`
statements like the one above.
```js
// script.min.js
// environment == 'production'
{
// Production only code ...
}
```
Generally, you need to ensure that rollup-plugin-consts goes _before_ other
things (like rollup-plugin-commonjs) in your `plugins` array, so that those
plugins can apply any optimisations such as dead code removal.
```js
// rollup.config.js
import consts from 'rollup-plugin-consts';
export default {
// ...
plugins: [
consts({
environment: 'production',
}),
],
};
```
## Options
```js
{
// All options are treated as `string: replacement` replacers...
testing: false,
version: '1.0.0',
environment: 'development',
// Objects can be used as replacements too!
config: { names: ['foo', 'bar'] },
}
```
## TypeScript
The `consts` function is has a typings file. See
[Usage with TypeScript](https://github.com/NotWoods/rollup-plugin-consts/wiki/Usage-with-TypeScript)
to check how to create additional typings files for importing constants.
## Credits
rollup-plugin-consts was originally created by
[Jake Archibald](https://github.com/jakearchibald/) for
[PROXX](https://github.com/GoogleChromeLabs/proxx). You can watch his
presentation with [Surma](https://github.com/surma/)
[about Rollup plugins they wrote for PROXX](https://youtu.be/TsTt7Tja30Q).
## License
Apache-2.0