一半需要我的图像转换为base64字符串，这样我们可以把我的形象到服务器。现在我们提供一个js：

function convertImgToBase64(url, callback, outputFormat){var canvas = document.createElement(‘CANVAS‘),        ctx = canvas.getContext(‘2d‘),        img =newImage;    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(‘http://bit.ly/18g0VNp‘,function(base64Img){// Base64DataURL});