Text Scramble Effect

index.html

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

script.typescript

// ——————————————————————————————————————————————————
// 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 from = oldText[i] || "";
      const to = newText[i] || "";
      const start = Math.floor(Math.random() * 40);
      const end = start + Math.floor(Math.random() * 40);
      this.queue.push({ from, to, start, end });
    }
    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 { from, to, start, end, char } = this.queue[i];
      if (this.frame >= end) {
        complete++;
        output += to;
      } else if (this.frame >= start) {
        if (!char || Math.random() < 0.28) {
          char = this.randomChar();
          this.queue[i].char = char;
        }
        output += `<span class="dud">${char}</span>`;
      } else {
        output += from;
      }
    }
    this.el.innerHTML = output;
    if (complete === this.queue.length) {
      this.resolve();
    } else {
      this.frameRequest = requestAnimationFrame(this.update);
      this.frame++;
    }
  }
  randomChar() {
    return this.chars[Math.floor(Math.random() * this.chars.length)];
  }
}

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

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

next();

style.stylus

@import 'https://fonts.googleapis.com/css?family=Roboto+Mono:100'
html, body
  font-family 'Roboto Mono', monospace
  background #010101
  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

styles

<link href="https://cdnjs.cloudflare.com/ajax/libs/colors.css/3.0.0/colors.min.css" rel="stylesheet" />
<link href="https://cdnjs.cloudflare.com/ajax/libs/animate.css/4.1.1/animate.min.css" rel="stylesheet" />

text-scramble-effect.markdown

Text Scramble Effect

A little text decoding / scramble effect

A Pen by Shane White on CodePen.

License.