What is the purpose of Vue.js watchers?

Watchers in Vue.js are used to reactively perform actions when a data property changes. They provide a way to observe specific data properties and execute a function in response to those changes.

To create a watcher, you simply define the property you want to watch inside the watch object of your Vue component:

export default {
  data() {
    return {
      count: 0
    };
  },
  watch: {
    count(newValue) {
      console.log(`Count changed to: ${newValue}`);
    }
  }
};

In this example, whenever the count property changes, the watcher will log the new value to the console. This is useful for performing side effects or updating external data based on user interactions.