As in Vue.js assign the value obtained from the props variable?

Why not use in the template the value of props, instead of to suffer with change tracking, etc.?

Well and so, you can certainly use a watch to watch for changes props's, and reassign whatever you need.

And what does it do? Because the values from the props negativny. Through watch https://codepen.io/VladIT4/pen/MGJwGO?editors=1010

UPD:

how to assign object

The object is even easier, because it is a reference type, then watch to do. The relationship is two sided. https://codepen.io/VladIT4/pen/VxPLVo?editors=1010 but it is better not to do that, we need an explicit relationship between the components, through the v-bind and event.