Plug-in to copy and modify file content
yarn add copy-modify-webpack-plugin
or
npm install copy-modify-webpack-plugin
const CopyModifyWebpackPlugins = require('copy-modify-webpack-plugins');
new CopyModifyWebpackPlugins({
entry: './index.js',
output: `./dir/index.js`,
callback: content => content.replace('searchValue', 'replacer')
})