javascript image preview - OhMinsSup/tip-review GitHub Wiki

    const reader = new FileReader();
    reader.addEventListener(
      'load',
      async () => {
        const response = await getS3FileUploadAPI({ file, fileType: 'PROFILE' });
        if (!response) {
          thumbail.src = 'assets/images/default.png';
          return;
        }

        const byteString = atob(reader.result.split(',')[1]);
        const ab = new Uint8Array(byteString.length);
        for (let i = 0; i < byteString.length; i++) {
          ab[i] = byteString.charCodeAt(i);
        }
        const blob = new Blob([ab], { type: file.type });
        const src = URL.createObjectURL(blob);
        thumbnail.src = src;
        thumbnail.setAttribute('data-path', response.path);
      },
      false,
    );
    if (file) {
      reader.readAsDataURL(file);
    }