framework/js/webpack.config.js

const config = require('flarum-webpack-config');
const webpack = require('webpack');
const merge = require('webpack-merge');

module.exports = merge(config(), {
    output: {
        library: 'flarum.core',
    },

    // use zepto instead of jquery
    module: {
        rules: [
            {
                test: require.resolve('zepto'),
                use: 'imports-loader?this=>window',
            },
        ],
    },
    resolve: {
        alias: {
            jquery: 'zepto',
        },
    },
});