index.js
function babel(options = {}) {
    return {
        name: 'babel',

        renderChunk(code) {
            options.presets = [['env', { modules: false }]];
            options.sourceMaps = true;
            return transform(code, options);
        }
    };
}
function babel(options = {}) {
    return {
        name: 'babel',

        renderChunk(code) {
            options.presets = [['env', { modules: false }]];
            options.sourceMaps = true;
            return transform(code, options);
        }
    };
}
function babel ( options = { } ) { return { name : 'babel' , renderChunk ( code ) { options . presets = [ [ 'env' , { modules : false } ] ] ; options . sourceMaps = true ; return transform ( code , options ) ; } } ; }
transpile after tree shaking
transpile after tree shaking