Javascript, the language of the browser first and foremost

funTimes.js

function funTimes() {
    let elements = document.getElementsByTagName('p');
    let counter = 0;

    setInterval(function() {  
        for (let i = 0; i < elements.length; i++) {
           generateRainbowText(elements[i], counter);
        }
        counter++;
    }, 200)
}

function generateRainbowText(element, counter) {
  var text = element.innerText;
  element.innerHTML = "";
  for (let i = 0; i < text.length; i++) {
    let charElem = document.createElement("span");
    charElem.style.color = "hsl(" + (360 * i * ((counter % 12) + 1 ) / text.length) + ",80%,50%)";
    charElem.innerHTML = text[i];
    element.appendChild(charElem);
  }
}

// Call forth the fun times!
funTimes()