<script>
export default {
  data() {
    return {
      arr: [0, 1, 2],
      obj: { name: 'chulsu' },
    };
  },
  watch: {

    arr: {
      handler(newValue, oldValue) {

        console.log(`old value : ${oldValue}`);
        console.log(`new value : ${newValue}`);

      },
      deep: true,

    },

    obj: {
      handler(newValue, oldValue) {

        console.log(`old value : ${JSON.stringify(oldValue)}`);
        console.log(`new value : ${JSON.stringify(newValue)}`);

      },
      deep: true,

    },
  },
}