10000 Digits of Pi

const target = 10000;

let current,result;

​

function setup() {

  noCanvas();

​

  current = createDiv();

  current.style("margin", "1em");

​

  result = createDiv();

  result.style("font-size", "16px");

  result.style("color", "black");

  result.style("background-color", "#e0e0e0");

  result.style("padding", "1em");

  result.style("margin", "1em");

  result.style("border-radius", "20px");

​

  const pi = new DigitsOfPi();

  setInterval(pi.update.bind(pi), 1);

  setInterval(pi.show.bind(pi), 25);

}

​

class DigitsOfPi {

  constructor() {

    this.count = 0;

    this.pi = "";

    this.k = 2n;

    this.a1 = 4n;

    this.b1 = 1n;

    this.a2 = 12n;

    this.b2 = 4n;

  }

  show(){

    current.html(`${this.count - 1}/${target}`);

    result.html(this.pi);    

  }

  update() {

    const p = this.k * this.k;

    const q = 2n * this.k + 1n;

    this.k += 1n;

    [this.a1, this.b1, this.a2, this.b2] = [

      this.a2,

      this.b2,

      p * this.a1 + q * this.a2,

      p * this.b1 + q * this.b2,

    ];

​

    let d1 = this.a1 / this.b1;

    let d2 = this.a2 / this.b2;

    while (d1 == d2) {

      this.throwToPI(d1);

      this.a1 = (this.a1 % this.b1) * 10n;

      this.a2 = (this.a2 % this.b2) * 10n;

      d1 = this.a1 / this.b1;

      d2 = this.a2 / this.b2;

    }

  }

​

  throwToPI(d) {

    if (this.count > target) return;

    if (this.count % 10 == 0) {

      d += this.count ? " " : ".<br>";

    }

    this.pi += d;

    this.count++;

​

  }

}

​