I recently read about ES6 const keyword and I can understand its importance when having something like this:

(function(){

    const PI = 3.14;

    PI = 3.15; //  Uncaught TypeError: Assignment to constant variable

})();

So, nobody can change my PI variable.

The misunderstanding I have is that I don't understand in which situation the use of const with objects can make sense (other than preventing people to do myObj = newValue;).

(function(){

    const obj = {a:1 ,b: 2, c:3};

    //obj = {x:7 , y:8, z: 9}

    //This is good

    //TypeError: Assignment to constant variable.



    obj.a=7; obj.b=8 ; obj.c=9;

    console.log(obj); //outputs: {a: 7, b: 8, c: 9}

})();

So when declaring an object: when should I say: Now I must declare my object with const?