js-将在线图片转成Base64的图片

convertImgToBase64:function(url, outputFormat,callback){
	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;}