图片转化成base64

function convertImgToBase64(url, callback, outputFormat){
var canvas = document.createElement('CANVAS'),
ctx = canvas.getContext('2d'),
img = new Image;
img.crossOrigin = 'Anonymous';
img.onload = function(){
canvas.height = img.height;
canvas.width = img.width;
ctx.drawImage(img,0,0);
var dataURL = canvas.toDataURL(outputFormat || 'image/png');
callback.call(this, dataURL);
canvas = null;
};
img.src = url;
}
convertImgToBase64(图片路径, function(base64Img){
//base64Img 生成的base64
})