_babel.config.js

const path = require('path');
module.exports = {
    presets: [
        [
            '@babel/preset-env', { 'loose': false }
        ],
        [
            '@vue/babel-preset-app',
            {
                'targets': {
                    'browsers': ['iOS >= 8', 'Android >=5']
                },
                'corejs': 3,
                'useBuiltIns': 'entry'
            }
        ]
    ],
    plugins: [
        // ['@babel/plugin-proposal-private-property-in-object', {'loose': true}],
        // ["@babel/plugin-proposal-private-methods", { "loose": true }],
        // ['@babel/plugin-proposal-class-properties', {'loose': true}],
        // [
        //     '@babel/plugin-transform-runtime',
        //     {
        //         'corejs': false,
        //         'helpers': true,
        //         'version': require('@babel/runtime/package.json').version,
        //         'regenerator': true,
        //         'useESModules': true,
        //         'absoluteRuntime': path.dirname(require.resolve('@babel/runtime/package.json'))
        //     }
        // ]
    ]
};