上传图片转为blob URL和计算文件大小

{
getFileUrl: function getFileUrl(fileInputId) {
    var uri = {
        url: '',
        filename: '',
        filetype: '',
        data: ''
    };

    var fileObj = typeof fileInputId === 'string' ? document.getElementById(fileInputId) : fileInputId;

    if (!utils.isCanUploadFileAsync || !fileObj) {
        return uri;
    }
    try {
        if (window.URL.createObjectURL) {
            var fileItems = fileObj.files;
            if (fileItems.length > 0) {
                var u = fileItems.item(0);
                uri.data = u;
                uri.url = window.URL.createObjectURL(u);
                uri.filename = u.name || '';
            }
        } else {
            // IE
            var u = document.getElementById(fileInputId).value;
            uri.url = u;
            var pos1 = u.lastIndexOf('/');
            var pos2 = u.lastIndexOf('\\');
            var pos = Math.max(pos1, pos2);
            if (pos < 0) uri.filename = u;else uri.filename = u.substring(pos + 1);
        }
        var index = uri.filename.lastIndexOf('.');
        if (index != -1) {
            uri.filetype = uri.filename.substring(index + 1).toLowerCase();
        }
        return uri;
    } catch (e) {
        throw e;
    }
},

getFileSize: function getFileSize(file) {
    var fileSize = this.getFileLength(file);
    if (fileSize > 10000000) {
        return false;
    }
    var kb = Math.round(fileSize / 1000);
    if (kb < 1000) {
        fileSize = kb + ' KB';
    } else if (kb >= 1000) {
        var mb = kb / 1000;
        if (mb < 1000) {
            fileSize = mb.toFixed(1) + ' MB';
        } else {
            var gb = mb / 1000;
            fileSize = gb.toFixed(1) + ' GB';
        }
    }
    return fileSize;
},

getFileLength: function getFileLength(file) {
    var fileLength = 0;
    if (file) {
        if (file.files) {
          if (file.files.length > 0) {
                fileLength = file.files[0].size;
            }
        } else if (file.select && 'ActiveXObject' in window) {
            file.select();
            var fileobject = new ActiveXObject('Scripting.FileSystemObject');
            var file = fileobject.GetFile(file.value);
            fileLength = file.Size;
        }
    }
    return fileLength;
}
}