Drop confetti effect when clicking button

Question

I use the following code to load some confetti animation, but it now loads on page load.

I want to start the effect when a <a href="#button">Confetti</a> is clicked.

How can I achieve this?

const canvasEl = document.querySelector('#canvas');

const w = canvasEl.width = window.innerWidth;
const h = canvasEl.height = window.innerHeight * 2;

function loop() {
  requestAnimationFrame(loop);
  ctx.clearRect(0, 0, w, h);

  confs.forEach((conf) => {
    conf.update();
    conf.draw();
  })
}

function Confetti() {
  //construct confetti
  const colours = ['#fde132', '#009bde', '#ff6b00'];

  this.x = Math.round(Math.random() * w);
  this.y = Math.round(Math.random() * h) - (h / 2);
  this.rotation = Math.random() * 360;

  const size = Math.random() * (w / 60);
  this.size = size < 15 ? 15 : size;

  this.color = colours[Math.floor(colours.length * Math.random())];

  this.speed = this.size / 4;

  this.opacity = Math.random();

  this.shiftDirection = Math.random() > 0.5 ? 1 : -1;
}

Confetti.prototype.border = function() {
  if (this.y >= h) {
    this.y = h;
  }
}

Confetti.prototype.update = function() {
  this.y += this.speed;

  if (this.y <= h) {
    this.x += this.shiftDirection / 3;
    this.rotation += this.shiftDirection * this.speed / 100;
  }

  if (this.y > h) this.border();
};

Confetti.prototype.draw = function() {
  ctx.beginPath();
  ctx.arc(this.x, this.y, this.size, this.rotation, this.rotation + (Math.PI / 2));
  ctx.lineTo(this.x, this.y);
  ctx.closePath();
  ctx.globalAlpha = this.opacity;
  ctx.fillStyle = this.color;
  ctx.fill();
};

const ctx = canvasEl.getContext('2d');
const confNum = Math.floor(w / 4);
const confs = new Array(confNum).fill().map(_ => new Confetti());

loop();

<canvas id="canvas"></canvas>