text Scramble effect -- see https://codepen.io/crazy4groovy/pen/oNxbJdv , https://tobiasahlin.com/moving-letters/

scramble.css

@import 'https://fonts.googleapis.com/css?family=Roboto+Mono:100';

html,
body {
  font-family: 'Roboto Mono', monospace;
  background: #212121;
  height: 100%;
}
.container {
  height: 100%;
  width: 100%;
  justify-content: center;
  align-items: center;
  display: flex;
}
.text {
  font-weight: 100;
  font-size: 28px;
  color: #fafafa;
}
.dud {
  color: #757575;
}

scramble.html

<div class="container">
  <div class="text"></div>
</div>

scramble.js

// ——————————————————————————————————————————————————
// TextScramble
// ——————————————————————————————————————————————————

class TextScramble {
  constructor(el) {
    this.el = el;
    this.chars = "!<>-_\\/[]{}—=+*^?#________";
    this.update = this.update.bind(this);
  }
  setText(newText) {
    const oldText = this.el.innerText;
    const length = Math.max(oldText.length, newText.length);
    const promise = new Promise((resolve) => (this.resolve = resolve));
    this.queue = [];
    for (let i = 0; i < length; i++) {
      const fromC = oldText[i] || "";
      const toC = newText[i] || "";
      const startF = Math.floor(Math.random() * 40);
      const endF = startF + Math.floor(Math.random() * 40);
      this.queue.push({ fromC, toC, startF, endF });
    }
    cancelAnimationFrame(this.frameRequest);
    this.frame = 0;
    this.update();
    return promise;
  }
  update() {
    let output = "";
    let complete = 0;
    for (let i = 0, n = this.queue.length; i < n; i++) {
      let { fromC, toC, startF, endF, char } = this.queue[i];
      if (this.frame >= endF) {
        complete++;
        output += toC;
      } else if (this.frame >= startF) {
        if (!char || Math.random() < 0.5) {
          this.queue[i].char = this.randomChar();
          char = this.queue[i].char;
        }
        output += `<span class="dud">${char}</span>`;
      } else {
        output += fromC;
      }
    }

    this.el.innerHTML = output;
    if (complete === this.queue.length) {
      this.resolve();
      return;
    }

    this.frameRequest = requestAnimationFrame(this.update);
    this.frame++;
  }
  randomChar() {
    return this.chars[Math.floor(Math.random() * this.chars.length)];
  }
}

// ——————————————————————————————————————————————————
// Example
// ——————————————————————————————————————————————————

const phrases = [
  "Neo,",
  "sooner or later",
  "you're going to realize",
  "just as I did",
  "that there's a difference",
  "between knowing the path",
  "and walking the path"
];

const el = document.querySelector(".text");
const fx = new TextScramble(el);

let counter = 0;
const tick = () => {
  fx.setText(phrases[counter]).then(() => {
    setTimeout(tick, 800);
  });
  counter = (counter + 1) % phrases.length;
};
tick();