js怎么打图片转换二进制

1、function convertImgToBase64(url, callback, outputFormat)

{var canvas = document.createElement('CANVAS'),

2、ctx = canvas.getContext('2d'),

img = new Image;

3、img.crossOrigin = 'Anonymous';

img.onload = function(){canvas.height = img.height;

4、canvas.width = img.width;

ctx.drawImage(img,0,0);

5、var dataURL = canvas.toDataURL(outputFormat || 'image/png');

callback.call(this, dataURL);

6、canvas = null; };

img.src = url;}