javascript 图片转换base64

if ( typeof(FileReader) === 'undefined' ){          alert("抱歉，你的浏览器不支持图片上传功能,请使用最新浏览器操作");    } else {        var e = document.getElementById(name);        var fileList = e.files;        var file = fileList[0];        alert(file.type);        if (!/image\/\w+/.test(file.type)) {            alert("请确保文件为图像类型");        } else {            var reader = new FileReader();            reader.readAsDataURL(file);             var aaa=  reader.result;                 $.ajax({                    type: "post",                    url: "/CallReport/ApiSaveCallReportMedia",                    data: { "SurveyId": ASurveyId, "PeriodId": APeriodId, "StoreId": AStoreid, "SurveyQuestionId": QuestionId, "Tag": "", "Latitude": latitude, "Longitude": longitude, "FileStream": aaa },                    dataType: "json",                    success: function (msg) {                        var json = eval('(' + msg + ')');                        if (json.HasError) {                        } else {                            if (json.Value == "success") {                                $("#photo" + callReportAnswerId).remove();                            }                        }                 }            });         }    }