rollup-plugin-postprocess 
Apply regex find-and-replace postprocessing to your Rollup bundle.
Installation
npm i -D rollup-plugin-postprocess
Usage
Works just like a JavaScript String replace, including the funtion callback option.
postprocess() expects an Array of [(RexExp) find, (String|Function) replace] pairs. Alternatively, if a function is provided, it will be invoked for each bundle and can return said pairs.
Example
import postprocess from 'rollup-plugin-postprocess';
export default {
plugins: [
postprocess([
[/\b(module\.exports=|export default )([a-zA-Z])/, '$1$2']
])
]
}Complex Example
This example is more practical. Rollup places exports at the end of your bundle, which can often create single-use variables that Uglify does not collapse. Let's implement a find & replace that "moves" the export inline to save some bytes.
In this example, we'll make use of the fact that find/replacement pairs are executed in sequence. The first pair is used both to remove the existing export statement and to find the export type & identifier. By the time the second find/replace pair is processed, it can make use of the values found in the first pass.
import postprocess from 'rollup-plugin-postprocess';
let name, exportPrefix;
export default {
plugins: [
postprocess([
[
/(module\.exports\s*=\s*|export\s*default\s*)([a-zA-Z$_][a-zA-Z0-9$_]*)[;,]?/,
(str, prefix, id) => {
name = id;
exportPrefix = prefix;
// returning nothing is the same as an empty string
}
],
[
/^function\s([a-zA-Z$_][a-zA-Z0-9$_]*)/,
(str, id) => id==name ? `${exportPrefix} function` : str
]
])
]
};