undefined result using prototype [javascript]

Question

So I'm learning prototype using javascript, and tried some code :

function Employee(name) { this.name= name; }
var m = new Employee("Bob");
var working= { isWorking: true };
Employee.prototype = working; 
alert(m.isWorking);

Unfortunately, I get an undefined message, instead of the true value. Is there a reason to this result?

I have made several tests. I've concluded that reassigning the prototype object causes any previously created instances of the Employee class to be unable to access any properties found inside the newly assigned prototype. Is this accurate?

Answer 1

Changing the prototype will not affect an already created object. It will only affect the objects created based on that object.

There is a property __proto__ which could be used to change the prototype, but its implementation is not required. ES6 does define setPrototypeOf method to change the prototype, but since it's only in ES6 the support may vary.