A snippet of code to use multiple instances of particle.js within the same page

particles-multiple.js

// Just add class "particle-js" to the elements you would like to load particles.js on. No need to pass each individual ID

window.onload = startParticles;
window.onresize = startParticles;
  
function startParticles() {
  var particleEls = document.getElementsByClassName("particles-js");

  if (particleEls) {
    Object.keys(particleEls).forEach(function(key) {
        loadParticles(particleEls[key]);
    });
  }
}
  
function loadParticles(el) {
  if(el.id === ""){
    el.id = randomId();
  }          

  particlesJS(el.id, PARAMS_JSON);
}

// Generates a random id
function randomId(){
  let string_length = 10;
  let random_string = '';
  let random_ascii;
  for(let i = 0; i < string_length; i++) {
      random_ascii = Math.floor((Math.random() * 25) + 97);
      random_string += String.fromCharCode(random_ascii)
  }
  return random_string
}

Little typo. Change
// Just add class "particle-js" to the elements you would...
to
// Just add class "particles-js" to the elements you would...