File API (from javascript)

https://www.html5rocks.com/zh/tutorials/file/dndfiles/

https://blog.johnsonlu.org/upload-file-with-file-api/

https://dwatow.github.io/2019/05-22-file-api/ . download

File API 中包含了幾個比較重要的 interface：

• File：可以用來讀取硬碟上檔案相關檔案資訊的物件
• FileList：File 物件的集合
• Blob：表示檔案內容的物件
• FileReader：讀取檔案用的物件

downloadFileBase64(fileID: string, imageName: string) {

            FileApi.getFile(fileID).then(fileData => {

                const element = document.createElement('a');

                element.setAttribute('href', `data:image/png;base64,${encodeURIComponent(fileData.file)}`);

                element.setAttribute('download', imageName);

                element.style.display = 'none';

                document.body.appendChild(element);

                element.click();

                document.body.removeChild(element);

            });

        },