4.15: Correction

<script setup>
  import {ref,reactive} from 'vue';
  let x=ref(0);  
  function bouger(e){
     console.log('input',e.pageX);
     x.value=e.pageX;
  }
</script>

<template>
   <p>Position X: <span>{{x}}</span></p>
   <div id="cadre" @mousemove="bouger"></div>
</template>

<style scoped>
#cadre{
   width: 300px;
   height: 300px;
   border: 1px solid black;
}
</style>