I want to tree shake lodash as well as my unused multiply function from the generated bundle from webpack

I have 2 main files app.js & math.js

It contains the following code -

app.js

import map from lodash/map;



import { sum } from ./math;



console.log(💩);



console.log(`2 + 3 = ${sum(2, 3)}`);



map([1, 2, 3], x => {

    console.log(x);

});

math.js

export const sum = (a, b) => a + b;

export const multiply = (m, n) => m * n;

webpack.config.js

const path = require(path);

const webpack = require(webpack);

const UglifyJSPlugin = require(uglifyjs-webpack-plugin);

const Jarvis = require(webpack-jarvis);



let plugins = [new Jarvis()];



if (process.env.NODE_ENV === production) plugins.push(new UglifyJSPlugin());



const config = {

    entry: ./app.js,

    output: {

        path: path.resolve(__dirname, dist),

        filename: bundle.js

    },

    module: {

        rules: [

            {

                test: /.js$/,

                exclude: /node_modules/,

                use: babel-loader

            }

        ]

    },

    plugins

};



module.exports = config;

My npm script look like -

scripts: {

    dev: webpack --optimize-minimize --mode development,

    dev:watch: webpack --watch --optimize-minimize --mode development,

    prod: webpack -p --optimize-minimize --mode production,

    prod:watch: webpack -p --watch --optimize-minimize --mode production,

    start: npm run prod,

    clean: rm -rf dist

  }

The complete code is available at https://github.com/deadcoder0904/webpack-treeshake

I've tried using UglifyJSPlugin but in the generated bundle it still shows my unused multiply function from math.js. Also, the production bundle generated from npm run prod remains 20kB which is a lot & I see a lot of lodash stuff included as well.