how to make nodejs exports a static object

i wonder to know is the code below runs right

a.js:

var obj = {
    name: 'a'
};
module.exports = obj;

b.js

var b = require('./a');

module.exports = b;

c.js

var a = require('./a');

console.log(a); // {name: 'a'}

a.name = 'b';
console.log(require('./a')); // {name: 'b'}
console.log(require('./b')); // {name: 'b'}

so, i can change a module exports from outside

if i cange the a.js to a.json

a.json

{
    "name": "a"
}

i got the same result

how can i export a module can't modify or override form outside