ps：网上爬来的一段代码：
<!--图片另存为--->
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title>通过js保存图片到本地 </title>
</head>
<body>
<!--创建一个cavas 用来存放图片-->
<div>
<div>
<canvas id="myCanvas" width="500" height="500" ></canvas>
</div>
<div>
<!-- 声明一个按钮 用来触发下载图片到本地-->
<input type="button" id="save" value="保存图片到本地" onclick="screenShot()"/>
</div>
</div>
</body>
</html>
<script>
var canvas=document.getElementById('myCanvas');
var ctx=canvas.getContext('2d');
ctx.fillStyle='#FF0000';
ctx.fillRect(0,0,80,100);
function screenShot()
{
var type ='png';
var d=document.getElementById("myCanvas");
var imgdata=d.toDataURL(type);
//2.0 将mime-type改为image/octet-stream,强制让浏览器下载
var fixtype=function(type)
{
type=type.toLocaleLowerCase().replace(/jpg/i,'jpeg');
var r=type.match(/png|jpeg|bmp|gif/)[0];
return 'image/'+r;
};
imgdata=imgdata.replace(fixtype(type),'image/octet-stream');
//3.0 将图片保存到本地
var date=new Date();
var filename=''+date.getHours()+':'+date.getMinutes()+":"+date.getSeconds()+'.'+type;
savaImage(imgdata,filename);
};
function savaImage(data,filename)
{
var save_link=document.createElementNS('http://www.w3.org/1999/xhtml', 'a');
save_link.href=data;
save_link.download=filename;
var event=document.createEvent('MouseEvents');
event.initMouseEvent('click',true,false,window,0,0,0,0,0,false,false,false,false,0,null);
save_link.dispatchEvent(event);
};
</script>