vue watch

<template>
  <div>
    <input v-model="message" />
    <p>{{ reversedMessage }}</p>
  </div>
</template>

<script>
export default {
  data() {
    return {
      message: '',
      reversedMessage: ''
    };
  },
  watch: {
    message(newVal) {
      this.reversedMessage = newVal.split('').reverse().join('');
    }
  }
};
</script>

In this example, a Vue component is created with an input field bound to the message data property and a paragraph element displaying the reversedMessage data property. The watch option is used to watch changes to the message property, and when it changes, the message is reversed and assigned to the reversedMessage property.