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

@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?


see my example below:

var btn = document.querySelector('button');
var hint = document.getElementById('hint');
var height = hint.clientHeight;
var width = hint.clientWidth;
console.log(width + 'x' + height);
// initialize them (within hint.style)
hint.style.height = height + 'px';
hint.style.width = width + 'px';

btn.addEventListener('click', function(){
  if(hint.style.visibility == 'hidden'){
    hint.style.visibility = 'visible';
    //hint.style.opacity = '1';
    hint.style.height = height + 'px';
    hint.style.width = width + 'px';
    hint.style.padding = '.5em';
  }
  else{
    hint.style.visibility = 'hidden';
    //hint.style.opacity = '0';
    hint.style.height = '0';
    hint.style.width = '0';
    hint.style.padding = '0';
  }

});
div#hint{
  background: gold;
  color: orangered;
  padding: .5em;
  box-sizing: border-box;
  overflow: hidden;

  font-weight: bold;
  transition: height 1s, width 1s, padding 1s, visibility 1s, opacity 0.5s ease-out;
}
<div id='hint'>
  
  <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> show hint </button>