如果图片不跨域，可以用canvas转一下，如果跨域，网上说加上 img.crossOrigin = 'Anonymous';管用，但是我测的是不管用的
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>canvas</title>
</head>
<body>
<img src="image/ab_photo.jpg" alt="" id="convertImg">
<script>
window.onload=function(){
function convertImgToBase64(url,fileobj){
document.createElement("div")
var canvas=document.createElement("canvas")
var c=canvas.getContext('2d')
img = new Image;
img.crossOrigin = 'Anonymous';
img.onload=function(){
canvas.height=fileobj.height;
canvas.width=fileobj.width;
c.drawImage(fileobj,0,0);
convertImg.src=canvas.toDataURL()
}
img.src=url;
}
var convertImg=document.getElementById("convertImg")
convertImgToBase64(convertImg.src,convertImg)
}
</script>
</body>
</html>
