vue watch child property

To watch a child property in Vue using the watch option, you can follow these steps:

1. Define the child property you want to watch in the component's data or computed property.
2. Add a watch option to the component's options, usually inside the created hook.
3. Within the watch option, define the child property as the key and a handler function as the value.
4. The handler function will be triggered whenever the child property changes.
5. The handler function receives two parameters: the new value and the old value of the child property.
6. You can perform any necessary logic or actions inside the handler function based on the changes in the child property.

Here's an example of how these steps can be implemented in a Vue component:

<template>
  <div>
    <h1>{{ childProperty }}</h1>
  </div>
</template>

<script>
export default {
  data() {
    return {
      childProperty: 'Initial value',
    };
  },
  watch: {
    childProperty(newValue, oldValue) {
      console.log(`Child property changed from ${oldValue} to ${newValue}`);
      // Perform any necessary logic or actions here
    },
  },
  created() {
    // Modify the child property to trigger the watch
    this.childProperty = 'New value';
  },
};
</script>

In this example, whenever the childProperty changes, the watch handler function will be triggered. The handler function will receive the new value and the old value of the childProperty, allowing you to perform any necessary actions or logic based on the changes.