rollup.config.js

import json from 'rollup-plugin-json';

export default [
    {
        input: 'src/extension.js',
        output: {
            file: 'extension/index.js',
            format: 'cjs'
        },
        plugins: [
            json({
                // All JSON files will be parsed by default,
                // but you can also specifically include/exclude files
                exclude: ['node_modules/**'],

                // for tree-shaking, properties will be declared as
                // variables, using either `var` or `const`
                preferConst: true, // Default: false

                // specify indentation for the generated default export —
                // defaults to '\t'
                indent: '  ',

                // ignores indent and generates the smallest code
                compact: true, // Default: false

                // generate a named export for every property of the JSON object
                namedExports: true // Default: true
            })
        ]
    },
]