watch changes object changes vue code example

Example 1: vue change deep element

Vue.set(vm.someObject, 'b', 2) //for objects
Vue.set(vm.items, indexOfItem, newValue) //forarrays

Example 2: vue watch object member

// Use a deep watcher for that:

watch: {
  item: {
     handler(val){
       // do stuff
     },
     deep: true
  }
}