Example for comment on SO answer: https://stackoverflow.com/a/65024713/630544

clone-example.js

/**
 * When creating a clone method for a class, keep in mind that object and array properties assigned to the clone
 * are passed by reference! This means modifying those properties on the clone will modify them on the original.
 * To avoid this, you need to clone the object and array property values as well.
 */
class Foo {
    constructor() {
        this.arr = []
    }

    static clone(foo) {
        const clone = new Foo()
        clone.arr = foo.arr
        return clone
    }
}

const foo = new Foo()
foo.arr.push('bar')
console.log(foo.arr) // ['bar']

const clone = Foo.clone(foo)
console.log(clone.arr) // ['bar']

foo.arr.push('baz')
console.log(foo.arr)   // ['bar', 'baz']
console.log(clone.arr) // ['bar', 'baz']