https://bernhardfritz.github.io/p8g/editor/e197e89a91af2582a2af44be9d8bcb00

sketch.js

import p8g, {
  background,
  createCanvas,
  height,
  line,
  noSmooth,
  random,
} from 'https://unpkg.com/p8g.js';

const merge = (left, right) => {
  const result = [];
  const leftValues = left.values();
  const rightValues = right.values();
  let leftValue = leftValues.next();
  let rightValue = rightValues.next();
  while (!leftValue.done && !rightValue.done) {
    if (leftValue.value <= rightValue.value) {
      result.push(leftValue.value);
      leftValue = leftValues.next();
    } else {
      result.push(rightValue.value);
      rightValue = rightValues.next();
    }
  }
  while (!leftValue.done) {
    result.push(leftValue.value);
    leftValue = leftValues.next();
  }
  while (!rightValue.done) {
    result.push(rightValue.value);
    rightValue = rightValues.next();
  }
  return result;
}

const mergeSort = (a, i = 0, n = a.length) => {
  if (n <= 1) {
    return a;
  }

  const h = Math.floor(n / 2);
  mergeSort(a, i, h);
  mergeSort(a, i + h, n - h);
  const merged = merge(a.slice(i, i + h), a.slice(i + h, i + n));
  for (let j = i; j < i + n; j++) {
    a[j] = merged[j - i];
  }

  return a;
}

const fisherYatesShuffle = (a) => {
  const n = a.length;
  for (let i = 0; i < n - 2; i++) {
    const j = Math.floor(random(i, n));
    [a[i], a[j]] = [a[j], a[i]];
  }
  return a;
};

function* makeIterator(fn, a) {
  const steps = [];
  const handler = {
    set(target, p, newValue) {
      steps.push([p, newValue]);
      target[p] = newValue;
      return true;
    },
  };
  const proxy = new Proxy([...a], handler);
  fn(proxy);
  for (const step of steps) {
    yield step;
  }
}

const n = 100;
const sorted = [...Array(n).keys()];
let it, a;
const init = () => {
  const unsorted = fisherYatesShuffle(sorted);
  it = makeIterator(mergeSort, unsorted);
  a = [...unsorted];
};
init();

p8g.draw = () => {
  background(255);
  noSmooth();
  a.forEach((y, x) => {
    line(x, height, x, height - y);
  });
  const { value, done } = it.next();
  if (done) {
    init();
  } else {
    const [x, y] = value;
    a[x] = y;
  }
};

createCanvas(n, n);