watch nested data 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 child property

...
watch:{
    'item.someOtherProp'(newVal){
        //to work with changes in "myArray"
    },
    'item.prop'(newVal){
        //to work with changes in prop
    }
}