JavaScript Fade

Sicherlich gibt es einige fertige Routinen um einen Fade Effekt zu erzielen, z.B. jQuery .fadeIn() und .fadeOut(), aber manchmal reicht auch die kleine Lösung.

fade functions.htm HTML (2,03 kByte) 16.03.2014 14:14
<!DOCTYPE html >
<html lang="en">
  <head><meta charset="utf-8" />
    <title>Simple Fade Example</title>
    <script type="text/javascript">
      /* <![CDATA[ */
window.requestAnimFrame = (function(){
  return  window.requestAnimationFrame       ||
          window.webkitRequestAnimationFrame ||
          window.mozRequestAnimationFrame    ||
          function(callback){
            window.setTimeout(callback, 1000 / 60);
          };
})();

function getOpacity(el, def) {
  var result;
  var style=document.defaultView.getComputedStyle(el, null);
  if ('opacity' in style) {
    result = style.opacity;
  } else if ('MozOpacity' in style) {
    result = style.MozOpacity;
  } else if ('filter' in style) {
    var match = style.filter.match(/alpha\(opacity=([\d.]+)\)/);
    if (match) {
      result = String(match[1] / 100);
    }
  }
  result = parseInt(result);
  if (!isNaN(result)) result = def;
  return result;
}

function setOpacity(el, val) {
  el.style.opacity = val;
  el.style.MozOpacity = val;
  el.style.filter = "alpha(opacity=" + (val*100) + ")";
}

function fadeIn(id) {
  var el = document.getElementById(id);
  var opacity = getOpacity(el, 0);
  var last = new Date();
  var tick = function() {
    opacity += (new Date() - last) / 400;
    setOpacity(el, (opacity>1 ? 1 : opacity));
    last = new Date();
    if (opacity < 1) { window.requestAnimFrame(tick); }
  };
  tick();
}

function fadeOut(id) {
  var el = document.getElementById(id);
  var opacity = getOpacity(el, 1);
  var last = new Date();
  var tick = function() {
    opacity -= (new Date() - last) / 400;
    setOpacity(el, (opacity<0 ? 0 : opacity));
    last = new Date();
    if (opacity > 0) { window.requestAnimFrame(tick); }  
  };
  tick();
}
/* ]]> */
    </script>
  </head>
  <body>
    <button onclick="fadeIn('el');">in</button>
    <button onclick="fadeOut('el');">out</button>
    <div id="el" style="display:block; background-color:silver; border:1px solid red; width:100px; height:100px;"></div>
  </body>
</html>
fade object.htm HTML (2,76 kByte) 16.03.2014 14:14
<!DOCTYPE html >
<html lang="en">
  <head><meta charset="utf-8" />
    <title>Simple Fade Example</title>
    <script type="text/javascript">
      /* <![CDATA[ */
window.requestAnimFrame = (function(){
  return  window.requestAnimationFrame       ||
          window.webkitRequestAnimationFrame ||
          window.mozRequestAnimationFrame    ||
          function(callback){
            window.setTimeout(callback, 1000 / 60);
          };
})();

if (!window.Element ) {
  Element = function(){};
}
Element.prototype.getOpacity = function(def) {
  var result;
  var style = document.defaultView.getComputedStyle(this, null);
  if ('opacity' in style) {
    result = style.opacity;
  } else if ('MozOpacity' in style) {
    result = style.MozOpacity;
  } else if ('filter' in style) {
    var match = style.filter.match(/alpha\(opacity=([\d.]+)\)/);
    if (match) {
      result = String(match[1] / 100);
    }
  }
  result = parseInt(result);
  if (!isNaN(result)) result = def;
  return result;
};
Element.prototype.setOpacity = function(val) {
  this.style.opacity = val;
  this.style.MozOpacity = val;
  this.style.filter = "alpha(opacity=" + (val*100) + ")";
};
Element.prototype.fadeIn = function() {
  var self = this;
  var opacity = this.getOpacity(0);
  var last = new Date();
  var tick = function() {
    opacity += (new Date() - last) / 400;
    self.setOpacity(opacity>1 ? 1 : opacity);
    last = new Date();
    if (opacity < 1) { window.requestAnimFrame(tick); }
  };
  tick();
};
Element.prototype.fadeOut = function() {
  var self = this;
  var opacity = this.getOpacity(1);
  var last = new Date();
  var tick = function() {
    opacity -= (new Date() - last) / 400;
    self.setOpacity(opacity<0 ? 0 : opacity);
    last = new Date();
    if (opacity > 0) { window.requestAnimFrame(tick); }
  };
  tick();
};
if (!window.Element ) {
  var __createElement = document.createElement;
  document.createElement = function(tagName) {
    var element = __createElement(tagName);
    if (element == null) {return null;}
    for (var key in Element.prototype)
      element[key] = Element.prototype[key];
    return element;
  }
  var __getElementById = document.getElementById;
  document.getElementById = function(id) {
    var element = __getElementById(id);
    if (element == null) {return null;}
    for (var key in Element.prototype)
      element[key] = Element.prototype[key];
    return element;
  }
}
/* ]]> */
    </script>
  </head>
  <body>
    <button onclick="document.getElementById('el').fadeIn();">in</button>
    <button onclick="document.getElementById('el').fadeOut();">out</button>
    <div id="el" style="display:block; background-color:silver; border:1px solid red; width:100px; height:100px;"></div>
  </body>
</html>

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