What's the difference between computed properties and methods?

A computed property is cached and re-evaluates only when its reactive dependencies change, while a method runs every time it is called. Use computed properties for derived values, and methods for actions such as event handlers.

• Computed properties are accessed like properties and should be pure functions, with no side effects. Reading one again returns the cached result until its dependencies change.
• Methods are called like functions and can have side effects. A method called in the template runs again on every re-render.

computed: {
  reversedMessage() {
    return this.message.split('').reverse().join('')
  }
},
methods: {
  reverseMessage() {
    this.message = this.message.split('').reverse().join('')
  }
}

Because of the cache, a computed that only reads Date.now() never updates, since Date.now() is not reactive. In <script setup>, a method is a plain function and a computed property is computed().