■概要 base64文字列で表現されたImageをUnit8Arrayコンストラクタ・Blobコンストラクタ・atobメソッドを利用して、Blob形式のfileに変換する方法。 ■コード //引数はbase64形式の文字列 function toBlob(base64) { var bin = atob(base64.replace(/^.*,/, '')); var buffer = new Uint8Array(bin.length); for (var i = 0; i < bin.length; i++) { buffer[i] = bin.charCodeAt(i); } // Blobを作成 try{ var blob = new Blob([buffer.buffer], { type: 'image/png' }); }catch (e){ return false; }
![JS: base64文字列をBlob形式のFileに変換する - Qiita](https://cdn-ak-scissors.b.st-hatena.com/image/square/20b41c6f8c8a3db69198c27fb8fe44f8b0520bdb/height=288;version=1;width=512/https%3A%2F%2Fqiita-user-contents.imgix.net%2Fhttps%253A%252F%252Fcdn.qiita.com%252Fassets%252Fpublic%252Farticle-ogp-background-9f5428127621718a910c8b63951390ad.png%3Fixlib%3Drb-4.0.0%26w%3D1200%26mark64%3DaHR0cHM6Ly9xaWl0YS11c2VyLWNvbnRlbnRzLmltZ2l4Lm5ldC9-dGV4dD9peGxpYj1yYi00LjAuMCZ3PTkxNiZoPTMzNiZ0eHQ9SlMlM0ElMjBiYXNlNjQlRTYlOTYlODclRTUlQUQlOTclRTUlODglOTclRTMlODIlOTJCbG9iJUU1JUJEJUEyJUU1JUJDJThGJUUzJTgxJUFFRmlsZSVFMyU4MSVBQiVFNSVBNCU4OSVFNiU4RiU5QiVFMyU4MSU5OSVFMyU4MiU4QiZ0eHQtY29sb3I9JTIzMjEyMTIxJnR4dC1mb250PUhpcmFnaW5vJTIwU2FucyUyMFc2JnR4dC1zaXplPTU2JnR4dC1jbGlwPWVsbGlwc2lzJnR4dC1hbGlnbj1sZWZ0JTJDdG9wJnM9ZDU4ZjAzYjNmZGU3MDg4ODIwN2RhNTA1MGI1ZjU3YjA%26mark-x%3D142%26mark-y%3D112%26blend64%3DaHR0cHM6Ly9xaWl0YS11c2VyLWNvbnRlbnRzLmltZ2l4Lm5ldC9-dGV4dD9peGxpYj1yYi00LjAuMCZ3PTYxNiZ0eHQ9JTQwcmNfY29kZSZ0eHQtY29sb3I9JTIzMjEyMTIxJnR4dC1mb250PUhpcmFnaW5vJTIwU2FucyUyMFc2JnR4dC1zaXplPTM2JnR4dC1hbGlnbj1sZWZ0JTJDdG9wJnM9NzdhNjVkNjMwMzg1Y2Y3OTdhMTY4ZmM3N2NjZmM1M2U%26blend-x%3D142%26blend-y%3D491%26blend-mode%3Dnormal%26s%3Dc71fc9f9010fbd6623a418c7cc5475ea)