The uglify target has been deprecated. Set the top level option `forceAllTransforms: true` instead. babel-preset-env: `DEBUG` option Using targets: { "chrome": "55" } Using modules transform: false Using plugins: check-es2015-constants {} transform-es2015-arrow-functions {} transform-es2015-block-scoped-functions {} transform-es2015-block-scoping {} transform-es2015-classes {} transform-es2015-computed-properties {} transform-es2015-destructuring {} transform-es2015-duplicate-keys {} transform-es2015-for-of {} transform-es2015-function-name {} transform-es2015-literals {} transform-es2015-object-super {} transform-es2015-parameters {} transform-es2015-shorthand-properties {} transform-es2015-spread {} transform-es2015-sticky-regex {} transform-es2015-template-literals {} transform-es2015-typeof-symbol {} transform-es2015-unicode-regex {} transform-regenerator {} transform-exponentiation-operator {} transform-async-to-generator {} syntax-trailing-function-commas { "chrome":"55" } Using polyfills with `entry` option: [src/in.js] Replaced `babel-polyfill` with the following polyfills: es7.string.pad-start { "chrome":"55" } es7.string.pad-end { "chrome":"55" } web.timers { "chrome":"55" } web.immediate { "chrome":"55" } web.dom.iterable { "chrome":"55" } src/in.js -> lib/in.js