js图片转base64编码压缩上传

/**
         * 回调函数
         * @param image_base64
         */
        var callback = function(image_base64) {
          ajaxPost('请求上传路径', {
            headImg: image_base64
          }, function (err, data) {
            if (err) {
              cb(err, null);
            } else {
              // 変更图片src
              $("#ImgId").attr("src", data.imgUrl);
            }
          });
        }

        /**
         * 头像选择触发事件
         */
        $(page).on('change', '#imgFileId', function () {
          fileUpload(this.files[0], callback);
        });

        /**
         * 将文件转成base64
         * @param obj
         * @param callback
         * @returns {boolean}
           */
        var fileUpload = function(obj, callback){
          var file = obj;
          //判断类型是不是图片
          if(!/image\/\w+/.test(file.type)){
            alert("请确保文件为图像类型");
            return false;
          }

          var reader = new FileReader();
          reader.readAsDataURL(file);
          reader.onload = function (e) {
            var img = new Image,
            width = 95,    //图片resize宽度
            quality = 1.0,  //图像质量
            canvas = document.createElement("canvas"),
            drawer = canvas.getContext("2d");
            img.src = this.result;
            canvas.width = width;
            canvas.height = width * (img.height / img.width);
            drawer.drawImage(img, 0, 0, canvas.width, canvas.height);
            img.src = canvas.toDataURL();
            var image_base64 = img.src.replace("data:image/png;base64,","");
            // 调用回调
            callback&&callback(image_base64);
          }
        }