rollup.config.js

// rollup.config.js
import resolve from 'rollup-plugin-node-resolve';
import commonjs from 'rollup-plugin-commonjs';
import babel from 'rollup-plugin-babel';

export default {
    external: ['chart.js'],
    output: {
        file: 'build/Plugin.Barchart.Background.js',
        format: 'umd',
        globals: {
            'chart.js': 'Chart'
        },
        name: 'PluginBarchartBackground'
    },
  plugins: [
    resolve(),
    commonjs(),
    babel()
  ]
};