How to sync two animations using css keyframes?

Question

I am working on solution

I have created a basic html banner where I want to keep image and text animations in sync.

Basically image animation is like scale logo for about 3 seconds, meanwhile logo is animated I want text for same in typing effect

I have created basic solution using css and javascript but it is not in sync

var typewriter = function(txt) {
  var container = document.getElementById('typewriter'),
    speed = 28,
    i = 0,
    wordsObj = txt.split(" ")
  container.textContent = "";
  runAllWords();

  function runAllWords() {

    if (i < wordsObj.length) {
      var a = (i == 0) ? i : i - 1;
      setTimeout(function() {
        showWord(wordsObj[i], 0)
      }, wordsObj[a].length * speed);
    }
  }

  function showWord(word, countWord) {
    if (countWord < word.length) {
      setTimeout(function() {
        showLetter(word, countWord)
      }, speed);
    } else {
      container.textContent = container.textContent + " ";
      i += 1;
      runAllWords();
    }
    if (i === wordsObj.length) {
      console.log('complete')
    }
  }

  function showLetter(word, countWord) {
    container.textContent = container.textContent + word[countWord];
    showWord(word, countWord + 1);
  }
}

var i = 0;

function myLoop() {
  //  create a loop function

  var dataType = document.getElementById('typewriter').dataset.typewriter,
    w = dataType.split(',')
  setTimeout(function() { //  call a 3s setTimeout when the loop is called
    typewriter(w[i]); //  your code here
    i++; //  increment the counter
    if (i < w.length) { //  if the counter < 10, call the loop function
      myLoop(); //  ..  again which will trigger another 
    } //  ..  setTimeout()
  }, 3000)
}

myLoop();

.addsp_320x50 {
  width: 100%;
  height: 50px;
  position: relative;
}

.addsp_320x50_img {
  position: absolute;
  top: 1px;
  left: 10px;
  width: 48px;
  height: 48px;
  border: 0px solid #ccc;
  border-radius: 50%;
}

.addsp_title_text {
  position: absolute;
  top: 5px;
  left: 70px;
  font-family: Open Sans;
  font-weight: bold;
}

.addsp_title_desc {
  position: absolute;
  top: 20px;
  left: 70px;
  font-family: Open Sans;
  color: #999;
}

.addsp_320x50_action button {
  height: 27px;
  background: #058562;
  border-radius: 4px;
  color: #fff;
  border-color: #058562;
  font-size: 12px;
  font-weight: bold;
  font-family: Open Sans;
  border-style: solid;
  position: absolute;
  right: 10px;
  top: 10px;
  display: flex;
}

.adz_text_1 {}

.adz_text_2 {
  animation: text2;
}

.adz_text_1,
.adz_text_2 {}

@keyframes text2 {
  0%,
  50%,
  100% {
    width: 0px;
  }
  60%,
  90% {
    width: 200px;
  }
}

@keyframes text1 {
  0%,
  50%,
  100% {
    width: 0px;
  }
  10%,
  40% {
    width: 200px;
  }
}

@media only screen and (min-width: 320px) {
  .addsp_320x50_img {
    width: 42px;
    height: 42px;
    top: 4px;
    left: 5px;
  }
  .addsp_title_text {
    top: 14px;
    left: 56px;
    font-size: 0.85rem;
  }
  .addsp_title_desc {
    top: 25px;
    left: 55px;
    font-size: 0.8rem;
  }
}

@media only screen and (min-width: 480px) {
  .addsp_title_text {
    top: 3px;
    left: 55px;
    font-size: 1.1rem;
  }
  .addsp_title_desc {
    top: 28px;
    left: 55px;
    font-size: 0.8rem;
  }
}

@media only screen and (min-width: 600px) {
  .addsp_title_text {
    top: 3px;
    left: 70px;
    font-size: 1.1rem;
  }
  .addsp_title_desc {
    top: 28px;
    left: 70px;
    font-size: 0.8rem;
  }
}

@media only screen and (min-width: 800px) {
  .addsp_title_text {
    top: 3px;
    left: 70px;
    font-size: 1.1rem;
  }
  .addsp_title_desc {
    top: 28px;
    left: 70px;
    font-size: 0.8rem;
  }
}

.addsp_320x50_img:nth-child(1) {
  animation-name: scale;
  animation-duration: 3s;
  animation-timing-function: linear;
  animation-delay: 1s;
  animation-iteration-count: infinite;
  animation-fill-mode: forwards;
  opacity: 0;
}

.addsp_320x50_img:nth-child(2) {
  animation-name: scale;
  animation-duration: 3s;
  animation-timing-function: linear;
  animation-delay: 4s;
  animation-iteration-count: infinite;
  animation-fill-mode: forwards;
  opacity: 0;
}

.addsp_320x50_img:nth-child(3) {
  animation-name: scale;
  animation-duration: 3s;
  animation-timing-function: linear;
  animation-delay: 7s;
  animation-iteration-count: infinite;
  animation-fill-mode: forwards;
  opacity: 0;
}

@keyframes scale {
  0% {
    transform: scale(1);
    opacity: 1
  }
  20% {
    transform: scale(1.2);
    opacity: 1
  }
  40% {
    transform: scale(1);
    opacity: 1
  }
  60% {
    transform: scale(1.2);
    opacity: 1
  }
  80% {
    transform: scale(1);
    opacity: 1
  }
  90% {
    transform: translateY(-100px);
    opacity: 0;
  }
  100% {
    opacity: 0;
  }
}

.blinking-cursor {
  color: #2E3D48;
  -webkit-animation: 1s blink step-end infinite;
  -moz-animation: 1s blink step-end infinite;
  -ms-animation: 1s blink step-end infinite;
  -o-animation: 1s blink step-end infinite;
  animation: 1s blink step-end infinite;
}

@keyframes "blink" {
  from,
  to {
    color: transparent;
  }
  50% {
    color: black;
  }
}

@-moz-keyframes blink {
  from,
  to {
    color: transparent;
  }
  50% {
    color: black;
  }
}

@-webkit-keyframes "blink" {
  from,
  to {
    color: transparent;
  }
  50% {
    color: black;
  }
}

@-ms-keyframes "blink" {
  from,
  to {
    color: transparent;
  }
  50% {
    color: black;
  }
}

@-o-keyframes "blink" {
  from,
  to {
    color: transparent;
  }
  50% {
    color: black;
  }
}

<div class="addsp_320x50">
  <img src="https://de7yjjf51n4cm.cloudfront.net/banners/amazonprime_newicon.jpg" class="addsp_320x50_img">
  <img src="https://de7yjjf51n4cm.cloudfront.net/banners/amazonprime_newicon.jpg" class="addsp_320x50_img">
  <img src="https://de7yjjf51n4cm.cloudfront.net/banners/amazonprime_newicon.jpg" class="addsp_320x50_img">
  <div class="addsp_title_text">
    <span class="adz_text_1 typewriter" id="typewriter" data-typewriter="Web Strategy,
    		UX Testing,
    		Content Management System,
    		Web Design,
    		Research and Analytics,
    		Information Architecture,
    		Strategic Consulting,Maintenance and Support"></span><span class="blinking-cursor">|</span>
  </div>
  <div class="addsp_320x50_action">
    <button>DOWNLOAD</button></div>
</div>

Answer 1

Mathematically speaking, sinking means adjusting frequency and phase. I'll demonstrate each separately. Note that what I'm gonna explain is the concept and you can implement it in your codes using Javascript, css, etc

Frequency

You can't sink two animations unless the longer duration is a factor of shorter duration.

For example in your codes, blinking has a duration of 1s. So your image scaling duration and Also the whole duration must be a selection of either 1s, 2s, 3s, ... or 1/2s, 1/3s, ...
For better understanding let me make a simple example. Assume two images want to be animated.

<img src="1.png" id="img1">
<img src="1.png" style="margin-left: 50px;" id="img2">  

Consider two different animations for each one

@keyframes k1
{
    25%
    {
        transform: rotate(-4deg);
    }
    50%
    {
        transform: rotate(0deg);
    }
    75%
    {
        transform: rotate(3deg);
    }
    100%
    {
        transform: rotate(0deg);
    }
}

@keyframes k2
{
    50%
    {
        transform: scale(1.2);
    }
    100%
    {
        transform: scale(1);
    }
}

So since k2 is simpler, I'll first assign it to img2 with duration of 0.7s

#img2
{
    animation: k2 0.7s linear infinite;
}

And based on what was explained, I will assign animation k1 to img1 with a duration of 1.4s. (NOT 1.3s NOT 1.5s VERY IMPORTANT!)

#img1
{
    animation: k1 1.4s linear infinite;
}

If you run this code you'll see they are sink! To feel the concept better, change the duration of k1 to 0.9s. Now it feels like they are doing their thing separately!
Note
I set k1 to 1.4s (0.7s × 2) because k1 seems to be a combination of one go forward and come back and using 2x feels they are dancing together with the same harmony!

Phase

In css, phase is showed by animation-delay. Modifying frequencies (duration) is enough to sink two animations but if two animation begin at the same time it will feel better! So to illustrate set a delay for img1 of 0.2s. They are still sink but it doesn't feel nice! Now change the delay to 0.7s. Now it's beautiful again! (Maybe even more beautiful)

Back to your code

Your images scale with duration of 1.2s (40% of 3s) and your text blinking duration is 1s and as you can see they are not factor of each other so you can't sink!

Answer 2

If you control the animation with the same JavaScript loop as the typewriter script, it won't lose sync. I rewrote the typewriter script to do this in the snippet below.

startTypewriter() Exaplaination

First, all the messages from the are collected converted into an array.

typewriter.getAttribute('data-typewriter').split(',');

Then the CSS icon animation is started. Because JavaScript intervals wait for their duration before executing their code, so the first message is typed by calling type() before the interval is created.

icon.classList.add('icon-animation');

type(typewriter, messages[0].trim(), animationDuration - pauseDuration);

The interval is now started, running every 3 seconds by default. The first thing that happens is the animation is reset in case it got out of sync somehow.

icon.classList.remove('icon-animation');
window.setTimeout(function() {
  icon.classList.add('icon-animation');
}, 25);

Next, the message is typed by calling type(). Before it ends, a check is run so see if it's on the last array element. If so, it will start over.

if (i == messages.length) i = 0;

type() Exaplaination

At the start, the timePerCharacter value is calculated. The message is split to an array and the typewriter output is cleared

var timePerCharacter = duration / message.length;
var message = message.split('');
typewriter.innerHTML = '';

A loop is created, running every timePerCharacter. The character is outputted to the typewriter output.

typewriter.innerHTML += message[i];

Once all the characters are outputted, the loop is cleared

if (i == message.length) clearInterval(typeLoop);

Snippent

var animationDuration = 3000;
var pauseDuration = 2000;

startTypewriter();

function startTypewriter() {
  var typewriter = document.getElementById('typewriter');
  var icon = document.getElementById('icon');
  var messages = typewriter.getAttribute('data-typewriter').split(',');
  
  icon.classList.add('icon-animation');
  
  type(typewriter, messages[0].trim(), animationDuration - pauseDuration);
    
  var i = 1;
  
  window.setInterval(function() {
    icon.classList.remove('icon-animation');
    window.setTimeout(function() {
      icon.classList.add('icon-animation');
    }, 25);
    
    type(typewriter, messages[i].trim(), animationDuration - pauseDuration);
    
    i++;
    
    if (i == messages.length) i = 0;
  }, animationDuration);
}

function type(typewriter, message, duration) {
  var timePerCharacter = duration / message.length;
  var message = message.split('');
  typewriter.innerHTML = '';

  var i = 0;

  var typeLoop = window.setInterval(function() {  
    typewriter.innerHTML += message[i];
    
    i++;
  
    if (i == message.length) clearInterval(typeLoop);
  }, timePerCharacter);
}

@keyframes icon {
  20% {
    transform: scale(0.9);
  }
  
  40% {
    transform: scale(1);
  }
  
  60% {
    transform: scale(0.9);
  }
  
  80% {
    transform: scale(1);
  }
  
  100% {
    transform: translateY(-200%);
  }
}

.icon {
  border-radius: 100%;
}

.icon-animation {
  animation: icon 3s;
}

@keyframes cursor {
  50% {
    color: transparent;
  }
}

.blinking-cursor {
  animation: cursor 1s steps(1) infinite;
}

<img id="icon" src="https://de7yjjf51n4cm.cloudfront.net/banners/amazonprime_newicon.jpg" class="icon">

<span id="typewriter" data-typewriter="
        Web Strategy,
    		UX Testing,
    		Content Management System,
    		Web Design,
    		Research and Analytics,
    		Information Architecture,
    		Strategic Consulting,
        Maintenance and Support
">
</span>
<span class="blinking-cursor">|</span>

Answer 3

I think you might be looking for the animation iteration event and the animation start event.

Instead of just using the myLoop function to call itself, try using these listeners to call it instead.

The end of your js file would look like:

var i = 0;

function myLoop() {
  var dataType = document.getElementById("typewriter").dataset.typewriter,
    w = dataType.split(",");

  if (i < w.length -1 ) {
    typewriter(w[i]);
  }

  i++;
}

var imageElems = Array.from(document.querySelectorAll('.addsp_320x50_img'));
imageElems.forEach(elem=>{
 elem.addEventListener('animationstart',myLoop);
});

Where ".addsp_320x50_img" is just whatever common selector you give to all the images.