/* 2015-09-28 上传图片*/    function convertImgToBase64(url, callback, outputFormat){         var canvas = document.createElement('CANVAS');         var ctx = canvas.getContext('2d');         var img = new Image;         img.crossOrigin = 'Anonymous';         img.onload = function(){          var width = img.width;          var height = img.height;          // 按比例压缩4倍          var rate = (width
     )              alert(base64Img);              // base64转图片不需要base64的前缀data:image/jpg;base64              alert(base64Img.split(",")[1]);            });            event.preventDefault();         });     /* 2015-09-28 */