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;

}

}