第一次写canvas相关的脚本，点击页面可以产生新的扩散点，并整体颜色变换，可以根据输入数字变换粒子大小，

预览地址：http://runjs.cn/code/58mct5yo

<!-- lang: js -->
/*

*@author-fanqie dc2002007@163.com */ window.requestAnimFrame = (function(){ return window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || function( callback ){ window.setTimeout(callback, 1000 / 60); }; })(); var openBtn=document.getElementById('J_open_btn'); var clearBtn=document.getElementById('J_clear_btn'); var runState=true; //打开关闭 openBtn.addEventListener("click",function(e){ thisBtn=e.target; if(runState==false){ runState=true; thisBtn.innerHTML="停止"; }else{ runState=false; thisBtn.innerHTML="继续"; } }); //J_clear_btn clearBtn.addEventListener("click",function(e){ liziDrawObj.destory(); runState=true; thisBtn.innerHTML="停止"; }); var mycanvas=document.getElementById('I_mycanvas'); mycanvas.height=window.innerHeight; mycanvas.width=window.innerWidth; var colors=['#00FF00','#FFFF00','#FF0000','#00CCFF']; var liziDrawClass=function(canvasObj,direction,directionVal,size,color){ this.canvasObj=canvasObj.getContext("2d"); this.direction=direction;//left top bottom right this.directionVal=directionVal;//偏移量 this.size=size; this.color=color; this.liziItem=Array();//粒子对象集合 } liziDrawClass.prototype={ //初始化 init:function(){ liziDrawObj.factory(250,200); this.canvasObj.shadowColor=this.color; this.canvasObj.fillStyle=this.color; this.canvasObj.globalAlpha=this.size; this.canvasObj.shadowBlur=5; this.canvasObj.save(); }, //渲染画布 drawDraw:function(lizi){ this.canvasObj.beginPath();

    this.canvasObj.arc(lizi.positionX,lizi.positionY,this.size,0,2*Math.PI);this.canvasObj.fill();this.canvasObj.closePath();this.canvasObj.restore();
},
//更新画布
update:function(){for(index in liziDrawObj.liziItem){liziDrawObj.liziItem[index]=liziDrawObj.createNew(liziDrawObj.liziItem[index],5);var liziList= liziDrawObj.liziItem[index];for(current in liziList){lizi=liziList[current];//liziDrawObj.canvasObj.clearRect(0,0,window.innerWidth,window.innerHeight);liziDrawObj.drawDraw(lizi);}}
},//同时创建多个新粒子 为了加快粒子产生速度
createNew:function(liziList,count){lastLizi=liziList.pop();liziList=Array();liziList.push(lastLizi);for (var i = 0; i <count; i++) {lastLizi=liziList[liziList.length-1];var liziNew=new liziClass(lastLizi.size,lastLizi.color,lastLizi.direction,lastLizi.positionX,lastLizi.positionY,lastLizi.directionVal);liziNew.centerX=lastLizi.centerX;liziNew.centerY=lastLizi.centerY;liziNew.angle=lastLizi.angle+0.15;liziNew.directionVal=lastLizi.directionVal+0.05;cx= liziNew.centerX+Math.sin(liziNew.angle) * liziNew.directionVal;cy= liziNew.centerY+Math.cos(liziNew.angle) * liziNew.directionVal;liziNew.positionX=cx+Math.random();liziNew.positionY=cy+Math.random()*5;liziList.push(liziNew);};return liziList;
},
//生产粒子model
factory:function(positionX,positionY){var lizi=new liziClass(this.size, this.color,this.direction,positionX,positionY,this.directionVal);this.liziItem.push([lizi]);this.color=colors[parseInt(Math.random()*4,10)];this.canvasObj.shadowColor=this.color;this.canvasObj.fillStyle=this.color;this.canvasObj.save();
},destory:function(){this.canvasObj.clearRect(0,0,window.innerWidth,window.innerHeight);this.liziItem=new Array();
}

} var liziClass=function(size,color,movement,positionX,positionY,directionVal){ this.size=size; this.color=color; this.movement=movement; this.positionX=positionX; this.positionY=positionY; this.centerX=Number(positionX)-directionVal; this.centerY=Number(positionY)-directionVal; this.angle=0; this.directionVal=directionVal;//偏移量 }

liziClass.prototype={}

var liziDrawObj=new liziDrawClass(mycanvas,'left',10,1,'#f0e');
liziDrawObj.init();function loop(){if(runState){liziDrawObj.size=document.getElementById('J_size').value;liziDrawObj.update();}requestAnimFrame(loop);}
mycanvas.addEventListener("click",newPosition);
function newPosition(e){if(runState){liziDrawObj.factory(e.x,e.y);}
}
loop();
<!-- lang: html --><a href="javascript:;" id="J_open_btn">停止</a>

<a href="javascript:;" id="J_clear_btn">清空</a> 粒子大小<input value="1" id="J_size" class="sizeInput" /> <canvas id="I_mycanvas" class="mycanvas" > 不支持…… </canvas>

<!-- lang: css -->
.mycanvas{background: #000}
body{background: #eee}

.sizeInput{width: 2em;font-size:15px; }