Example for destructuring

destructuring.js

// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment
class TestClass {
    constructor({a = 1, b = 2, c, d, ...extra} = {d: 4}) {
        this.data = {a, b, c, d};
        this.extra = extra;
    }

    toString() {
        console.log(`a = ${this.data.a}, b = ${this.data.b}, c = ${this.data.c}, d = ${this.data.d}, extra = ${this.extra}`)
    }
}

const noparam = new TestClass();
console.log('no param', noparam);

const onlya = new TestClass({a: 3});
console.log('only a', onlya);

const addc = new TestClass({c: 3});
console.log('add c', addc);

const withExtra = new TestClass({ex: 3});
console.log('with extra', withExtra);

/*
The result of above code

noparam TestClass { data: { a: 1, b: 2, c: undefined, d: 4 }, extra: {} }
onlya TestClass { data: { a: 3, b: 2, c: undefined, d: undefined }, extra: {} }
addc TestClass { data: { a: 1, b: 2, c: 3, d: undefined }, extra: {} }
withExtra TestClass { data: { a: 1, b: 2, c: undefined, d: undefined }, extra: { ex: 3 } }

 */