日期:2014-05-16  浏览次数:20623 次

html5学习canvas基本使用:div在js前面;localStorage存储根据浏览器在不同的位置;应用程序缓存;placeholder 属性提供一种提示(hint),描述输入域所期待的值。
 <body>
<canvas id="myCanvas" width="300px;" height="200px"
style="border:1px solid #00ff00;"></canvas>
	<script  type="text/javascript">
	var c=document.getElementById("myCanvas");
var cxt=c.getContext("2d");
cxt.moveTo(0,0);
cxt.lineTo(150,60);
cxt.lineTo(10,60);
cxt.stroke();
	</script>
	<hr>
	<br>
	<canvas id="myCanvas2" width="300px;" height="200px"style="border:1px solid #00ff00;"></canvas>
	<script  type="text/javascript">
	var c=document.getElementById("myCanvas2");
var cxt=c.getContext("2d");
cxt.fillStyle="#ff0000";
cxt.beginPath();
cxt.arc(70,18,15,0,Math.PI*2,true);//画弧context.arc(x, y, radius, startAngle, endAngle, anticlockwises)
cxt.closePath();
cxt.fill();
	</script>
  </body>
localstorage基本使用方法如下:默认存数的是字符串类型
if(localStorage.pageCount){
		localStorage.pageCount=Number(localStorage.pageCount)+1;//pageCount自定义的

	}
	else{
	localStorage.pageCount=1;
	}
	document.write("visit"+localStorage.pageCount+"time(s)");
	</script>