Cannot assign to read only property 'name' of object '[object Object]'

The name is reserved property of Function object to which you are trying to set it in. You cannot set it.

documentation for name property is at MDN.

If you get this error in Angular+TypeScript:

WRONG / INVALID:

@Output whatever_var = new EventEmitter();

GOOD / CORRECT:

@Output() whatever_var = new EventEmitter();

If you get this error in Angular+Typescript+NgRX:

You can use the spread operator to take a shallow copy of a readonly object to make it readable, however you may not want this depending on your situation.

let x = [...y];

If you're using Redux / NgRX, there's a chance your selector could be returning a readonly object with a reference to the store, which can throw exceptions when trying to alter that object property via template binding. Depending on your situation, you can take a deep copy to remove the store reference.

let x = JSON.parse(JSON.stringify(y));

You cannot modify the name property of a function. The descriptor says it is not writable...

var BaseClass = function (data) {
  Object.assign(this, data);
};

console.log(Object.getOwnPropertyDescriptor(BaseClass, 'name'));

But since it is configurable, you could use Object.defineProperty().

var BaseClass = function (data) {
  Object.assign(this, data);
};

Object.defineProperty(BaseClass, 'name', {
  writable: true,
  value: 'Foo'
});

console.log(BaseClass.name);

EDIT

I'm back! So... As I said previously in comments, I think I have identified your problem. I answered a bit too fast and did not see that your ES5 inheritance is wrong.

ExtendedClass.prototype = Object.create(BaseClass); is not what you want to do. Doing so means the prototype of ExtendedClass becomes a constructor function. This obviously generates an unexpected behavior.

function BaseClass(data) {
  console.log(this instanceof BaseClass); // "this" is not an instance of "BaseClass"
  console.log(this instanceof Function); // "this" is a function
  console.log(this.name); // "this" is "BaseClass"
  
  Object.assign(this, data);
}

function ExtendedClass() {
  BaseClass.apply(this, arguments);
}
ExtendedClass.prototype = Object.create(BaseClass);

new ExtendedClass({ type: 'foo' });

In your code, this is a function and refers to BaseClass. That is why you are not allowed to modify its name...

In fact, when working with inheritance in JavaScript, you generally need these two lines:

ExtendedClass.prototype = Object.create(BaseClass.prototype);
ExtendedClass.prototype.constructor = ExtendedClass;

Here is a valid implementation:

function BaseClass(data) {
  console.log(this instanceof BaseClass); // "this" is an instance of "BaseClass"
  console.log(this instanceof Function); // "this" is not a function
  console.log(this.name); // "this" has no name yet
  
  Object.assign(this, data);
}

function ExtendedClass() {
  BaseClass.apply(this, arguments);
}
ExtendedClass.prototype = Object.create(BaseClass.prototype);
ExtendedClass.prototype.constructor = ExtendedClass;

var instance = new ExtendedClass({ name: 'foo' });

console.log(instance.name); // foo
console.log(BaseClass.name); // BaseClass
console.log(ExtendedClass.name); // ExtendedClass