1watch(
2  colours,
3  () => {
4    console.log('The list of colours has changed!');
5  },
6  {
7    deep: true,
8  }
9);

1export default {
2  name: 'ColourChange',
3  props: {
4    colours: {
5      type: Array,
6      required: true,
7    },
8  },
9  watch: {
10    // Use the object syntax instead of just a method
11    colours: {
12      // This will let Vue know to look inside the array
13      deep: true,
14
15      // We have to move our method to a handler field
16      handler()
17        console.log('The list of colours has changed!');
18      }
19    }
20  }
21}