Fibonacci class JavaScript

class fib {
    constructor() {
        this.a = (function*() {
            let a = 0,
                b = 1;
            yield 0;
            while (true) {
                let t = a + b;
                a = b;
                yield b = t
            }
        })()
    }
    get next() {
        return this.a.next().value;
    }
}