old_contents: var count = document.getElementById("count");
  var canvas = document.getElementById("canvas");
  var dc = canvas.getContext("2d");
  
  var ms = new Array();
  
  var gen_color = function(){
    return "rgb(" +
      parseInt(Math.random()*255) + "," +
      parseInt(Math.random()*255) + "," +
      parseInt(Math.random()*255) + ")";
  }
  var on_click = function(){
    for(i=0;i<count.value;i++){
      obj = {
        x : 640, y : 100,
        sx : Math.random() * 10 - 5, sy : Math.random() * 10,
        alpha : 255,
        size : parseInt(Math.random() * 20 + 10),
        color : gen_color()
      }
      ms.push( obj );
    }
  }
  
  setInterval( function(){
    dc.clearRect(0,0,1280,960);
    dc.globalCompositeOperation = "lighter";
    
    var grd = dc.createRadialGradient(75,50,5,90,60,100);
    grd.addColorStop(0,"red");
    grd.addColorStop(1,"white");
    
  
    for( var i in ms ){
      var obj = ms[i];
      
      dc.font = obj.size + "px Arial";
      dc.globalAlpha = obj.alpha / 255;
      dc.fillStyle = grd;
      dc.fillText( "민수천재야", obj.x,obj.y );
      
      obj.x += obj.sx;
      obj.y += obj.sy;
      obj.alpha -= 2.5;
      
      if( obj.alpha == 0 ){
        ms.splice( i, 1 );
      }
    }
    
    dc.fill();
  }, 33 );
  
new_contents: var count = document.getElementById("count");
  var canvas = document.getElementById("canvas");
  var dc = canvas.getContext("2d");
  
  var ms = new Array();
  
  var gen_color = function(){
    return "rgb(" +
      parseInt(Math.random()*255) + "," +
      parseInt(Math.random()*255) + "," +
      parseInt(Math.random()*255) + ")";
  }
  var on_click = function(){
    for(i=0;i<count.value;i++){
      obj = {
        x : 640, y : 100,
        sx : Math.random() * 10 - 5, sy : Math.random() * 10,
        alpha : 255,
        size : parseInt(Math.random() * 20 + 10),
        color : gen_color()
      }
      ms.push( obj );
    }
  }
  
  setInterval( function(){
    dc.clearRect(0,0,1280,960);
    dc.globalCompositeOperation = "lighter";
    
    for( var i in ms ){
      var obj = ms[i];
      
      dc.font = obj.size + "px Arial";
      dc.globalAlpha = obj.alpha / 255;
      dc.fillStyle = obj.color;
      dc.fillText( "민수천재야", obj.x,obj.y );
      
      obj.x += obj.sx;
      obj.y += obj.sy;
      obj.alpha -= 2.5;
      
      if( obj.alpha == 0 ){
        ms.splice( i, 1 );
      }
    }
    
    dc.fill();
  }, 33 );
  
subject: Update minsoo.js