报错

 WARNING  Compiled with 17 warnings                                                                                  下午1:06:12

 warning  in ./node_modules/vue-router/dist/vue-router.esm-bundler.js

"export 'computed' was not found in 'vue'

 warning  in ./src/router/index.js

"export 'default' (imported as 'Router') was not found in 'vue-router'

 warning  in ./node_modules/vue-router/dist/vue-router.esm-bundler.js

"export 'defineComponent' was not found in 'vue'

 warning  in ./node_modules/vue-router/dist/vue-router.esm-bundler.js

"export 'getCurrentInstance' was not found in 'vue'

 warning  in ./node_modules/vue-router/dist/vue-router.esm-bundler.js

"export 'h' was not found in 'vue'

 warning  in ./node_modules/vue-router/dist/vue-router.esm-bundler.js

"export 'inject' was not found in 'vue'

 warning  in ./node_modules/vue-router/dist/vue-router.esm-bundler.js

"export 'nextTick' was not found in 'vue'

 warning  in ./node_modules/vue-router/dist/vue-router.esm-bundler.js

"export 'onActivated' was not found in 'vue'

 warning  in ./node_modules/vue-router/dist/vue-router.esm-bundler.js

"export 'onDeactivated' was not found in 'vue'

 warning  in ./node_modules/vue-router/dist/vue-router.esm-bundler.js

"export 'onUnmounted' was not found in 'vue'

 warning  in ./node_modules/vue-router/dist/vue-router.esm-bundler.js

"export 'provide' was not found in 'vue'

 warning  in ./node_modules/vue-router/dist/vue-router.esm-bundler.js

"export 'reactive' was not found in 'vue'

 warning  in ./node_modules/vue-router/dist/vue-router.esm-bundler.js

"export 'ref' was not found in 'vue'

 warning  in ./node_modules/vue-router/dist/vue-router.esm-bundler.js

"export 'shallowRef' was not found in 'vue'

 warning  in ./node_modules/vue-router/dist/vue-router.esm-bundler.js

"export 'unref' was not found in 'vue'

 warning  in ./node_modules/vue-router/dist/vue-router.esm-bundler.js

"export 'watch' was not found in 'vue'

 warning  in ./node_modules/vue-router/dist/vue-router.esm-bundler.js

"export 'watchEffect' was not found in 'vue'

原因

路由版本冲突，因为默认下载的是最新版，支持vue3，而我用的是vue2

解决办法

npm install vue-router@3.0.2