JavaScript - add transition between display:none and display:block

Question

I am using JavaScript to toggle notification like below. How can I add transition between display: block and display: none;

I don\'

Answer 1

@vothaison's suggestion: CSS transitions

Technically, @vothaison wanted to use setInterval as opposed to setTimeout, but I don't see the need for that. It's just more work.

var hint = document.getElementById('hint');
var btn = document.getElementById('btn_show');

btn.addEventListener('click', function(){
  var ctr = 1;
  hint.className = hint.className !== 'show' ? 'show' : 'hide';
  if (hint.className === 'show') {
    hint.style.display = 'block';
    window.setTimeout(function(){
      hint.style.opacity = 1;
      hint.style.transform = 'scale(1)';
    },0);
  }
  if (hint.className === 'hide') {
    hint.style.opacity = 0;
    hint.style.transform = 'scale(0)';
    window.setTimeout(function(){
      hint.style.display = 'none';
    },700); // timed to match animation-duration
  }
 
});

#hint {
  background: yellow;
  color: red;
  padding: 16px;
  margin-bottom: 10px;
  opacity: 0;
  transform: scale(0);
  transition: .6s ease opacity,.6s ease transform;
}

<div id="hint" style="display: none;">
  <p>This is some hint on how to be safe in this community </p>
  <p>This is another hint on how to be safe in this community </p>
</div>

<button id="btn_show"> Show hint </button>

Using CSS animations

var hint = document.getElementById('hint');
var btn = document.getElementById('btn_show');

btn.addEventListener('click', function(){
  hint.className = hint.className !== 'show' ? 'show' : 'hide';
  if (hint.className === 'show') {
    setTimeout(function(){
      hint.style.display = 'block';
    },0); // timed to occur immediately
  }
  if (hint.className === 'hide') {
    setTimeout(function(){
      hint.style.display = 'none';
    },700); // timed to match animation-duration
  }
});

@-webkit-keyframes in {
  0% { -webkit-transform: scale(0) rotate(12deg); opacity: 0; visibility: hidden;  }
  100% { -webkit-transform: scale(1) rotate(0); opacity: 1; visibility: visible; }
}

@keyframes in {
  0% { transform: scale(0) rotate(12deg); opacity: 0; visibility: hidden;  }
  100% { transform: scale(1) rotate(0); opacity: 1; visibility: visible; }
}

@-webkit-keyframes out {
  0% { -webkit-transform: scale(1) rotate(0); opacity: 1; visibility: visible; }
  100% { -webkit-transform: scale(0) rotate(-12deg); opacity: 0; visibility: hidden; }
}

@keyframes out {
  0% { transform: scale(1) rotate(0); opacity: 1; visibility: visible; }
  100% { transform: scale(0) rotate(-12deg); opacity: 0; visibility: hidden;  }
}

#hint {
  background: yellow;
  color: red;
  padding: 16px;
  margin-bottom: 10px;
}

#hint.show {
  -webkit-animation: in 700ms ease both;
  animation: in 700ms ease both;
}

#hint.hide {
  -webkit-animation: out 700ms ease both;
  animation: out 700ms ease both;
}

<div id="hint" style="display: none;">
  <p>This is some hint on how to be safe in this community </p>
  <p>This is another hint on how to be safe in this community </p>
</div>

<button id="btn_show"> Show hint </button>

---

Using vanilla JavaScript

There are many, many ways to do this sort of thing with vanilla JavaScript, so here's a quick sketch of one way:

// you may need to polyfill requestAnimationFrame

var hint = document.getElementById('hint');
var btn = document.getElementById('btn_show');

btn.addEventListener('click', function(){
  var ctr = 0;
  hint.className = hint.className !== 'show' ? 'show' : 'hide';
  
  if (hint.className === 'show') {
    window.setTimeout(function(){
      hint.style.display = 'block';
      fadein();
    },0); // do this asap        
  }
  
  if (hint.className === 'hide') {
    fadeout();
    window.setTimeout(function(){
      hint.style.display = 'none';
    },700); // time this to fit the animation
  }
  
  function fadein(){
    hint.style.opacity = ctr !== 10 ? '0.'+ctr : 1;
    hint.style.transform = ctr !== 10 ? 'scale('+('0.'+ctr)+')' : 'scale(1)';
    ctr++;
    
    if (ctr < 11)
      requestAnimationFrame(fadein);
    
    else
      ctr = 0;
  }

  function fadeout(){
    hint.style.opacity = 1 - ('0.'+ctr);
    hint.style.transform = 'scale('+(1 - ('0.'+ctr))+')';
    ctr++;
    
    if (ctr < 10)
      requestAnimationFrame(fadeout);
    else
      ctr = 0;
  }
});

#hint {
  background: yellow;
  color: red;
  padding: 16px;
  margin-bottom: 10px;
  opacity: 0;
}

<div id="hint" style="display: none;">
  <p>This is some hint on how to be safe in this community </p>
  <p>This is another hint on how to be safe in this community </p>
</div>

<button id="btn_show"> Show hint </button>

Say what you want about GreenSock, Velocity.js, jQuery, etc — they all trivialise this process of showing and hiding of things. Why not just borrow the show and hide functions from jQuery's source code?