What I found by reading source code

Question 1

Static method

Answer 1

A static method (or static function) is a method defined as a member of an object but is accessible directly from an API object’s constructor, rather than from an object instance created via the constructor.

https://developer.mozilla.org/en-US/docs/Glossary/Static_method

Question 2

Object.getOwnPropertyDescriptor()

Answer 2

this static method returns an object describing the configuration of a specific property on a given object (that is, one directly present on an object and not in the object’s prototype chain)

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/getOwnPropertyDescriptor

Question 3

Object.freeze()

Answer 3

A frozen object can no longer be changed

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/freeze

Question 4

Object.defineProperty()

Answer 4

defines a new property directly on an object, or modifies an existing property on an object, and returns the object.

Object.defineProperty(object1, ‘property1’, {
value: 42,
writable: false
});

Question 5

get syntax

Answer 5

binds an object property to a function that will be called when that property is looked up

const obj = {
log: [‘a’, ‘b’, ‘c’],
get latest() {
return this.log[this.log.length - 1];
}
};

Question 6

getters and setters

Answer 6

https://javascript.info/property-accessors

Question 7

Destructuring assignment: lists

Answer 7

let [firstName, surname] = [“John”, “Smith”]

https://javascript.info/destructuring-assignment

Question 8

CustomEvent: detail property

Answer 8

// create custom events
const catFound = new CustomEvent(“animalfound”, {
detail: {
name: “cat”,
},
});
// add an appropriate event listener
obj.addEventListener(“animalfound”, (e) => console.log(e.detail.name));
// dispatch custom event
obj.dispatchEvent(catFound);

https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent/detail

Question 9

Object.seal()

Answer 9

similar to Object.freeze() but you may change property values; maily, you cannot add/delete properties, but may change values of existing ones

https://devdocs.io/javascript/global_objects/object/seal

Question 10

Object.assign(target, …sources)

Answer 10

static method copies all enumerable own properties from one or more source objects to a target object.

It returns the modified target object

(! leave the target alone) Object.assign({}, …[target, …source])

(better yet) const obj = {…{1:1, 2:2}, 3:3}

Question 11

Symbol

Answer 11

primitive unique value. immutable.