安装elementui时出现警告：
npm WARN deprecated core-js@2.6.12: core-js@❤️.23.3 is no longer maintained and not recommended for usage due to the number of issues. Because of the V8 engine whims, feature detection in old core-js versions could cause a slowdown up to 100x even if nothing is polyfilled. Some versions have web compatibility issues. Please, upgrade your dependencies to the actual version of core-js.
这表明你的core-js的版本低了。
解决方法
npm i core-js
