WARNING: We noticed you're using the `useBuiltIns` option without declaring a core-js version. Currently, we assume version 2.x when no version is passed. Since this default version will likely change in future versions of Babel, we recommend explicitly setting the core-js version you are using via the `corejs` option. You should also be sure that the version you pass to the `corejs` option matches the version specified in your `package.json`'s `dependencies` section. If it doesn't, you need to run one of the following commands: npm install --save core-js@2 npm install --save core-js@3 yarn add core-js@2 yarn add core-js@3 Successfully compiled 1 file with Babel.
{ "presets": [ ["@babel/env", { "targets": { "edge": "17", "firefox": "60", "chrome": "67", "safari": "11.1" }, "useBuiltIns": "usage", "corejs": "2" //是因为少了这行代码(运行时去掉注释) } ] ] }