<!DOCTYPE html> <html> <head> <script src="a.js"></script> </head> <body> <div id="root"></div> </body> <script> const app = Vue.createApp({ template:` <layout> <template v-slot:header> <div>header</div> </template> <template v-slot:footer> <div>footer</div> </template> </layout> ` }) app.component('layout',{ template:` <div> <slot name="header"></slot> <div>content</div> <slot name="footer"></slot> </div> ` }) const vm = app.mount('#root') </script> </html>