# only-if-changed-webpack-plugin

Webpack plugin to only run build if dependent files have changed

## Example

```js
var path = require('path')
var OnlyIfChangedPlugin = require('only-if-changed-webpack-plugin')

var opts = {
    rootDir: process.cwd(),
    devBuild: process.env.NODE_ENV !== 'production',
}

module.exports = {
    output: {
        filename: 'bundle.js',
        path: path.join(opts.rootDir, 'build'),
        pathinfo: opts.devBuild,
    },
    plugins: [
        new OnlyIfChangedPlugin({
            cacheDirectory: path.join(opts.rootDir, 'tmp/cache'),
            cacheIdentifier: opts, // all variable opts/environment should be used in cache key
        }),
    ],
}
```

After a successful build, all subsequent builds will skip compiling and emitting
assets unless an input file dependency or output asset of the build has been
modified or deleted.

### See also

-   [cached-loader](https://github.com/jsdf/cached-loader) – Adds persistent on-disk caching to webpack loaders