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Excel/CSVからJSON・HTML・PDF相互変換ツール
Excel/CSVからJSON・HTML・PDF相互変換ツール
本ツールは100%クライアントサイド（ブラウザ内）で動作します。コード、トークン、機密データが外部サーバーに送信されることは一切ありません。
コアアーキテクチャ & 計算式
File Buffer (.xlsx) ➔ Binary Parsing ➔ Worksheet Extraction ➔ JSON Array Matrix
The parser unzips the XLSX archive, reads the internal XML mapping relationships, extracts the specific worksheet grid, and maps the top row as the structural keys for the JSON objects.
ベストプラクティスとガイドライン
- Clean Your Top Row Headers: The converter uses row 1 as the JSON keys. Ensure row 1 does not contain merged cells, empty gaps, or duplicate names. Use strict camelCase (e.g., `firstName`) for developer friendly output.
- Remove Hidden Metadata: Excel files often contain hidden sheets, massive blank columns, and macro metadata. Highlight and delete all unused columns to dramatically reduce the JSON output payload size.
- Format Dates as Text Before Export: Excel handles dates bizarrely (as the number of days since Jan 1, 1900). To prevent the JSON from outputting raw integers like `44197`, explicitly format your date columns as 'Text' (YYYY-MM-DD) inside Excel before converting.
よくある質問 (FAQ)
Why is the converter outputting an empty file?
You likely have the wrong worksheet selected. An Excel workbook can contain dozens of tabs. Ensure you specify exactly which sheet (e.g., 'Sheet1') you want to extract.
Are my formulas preserved in the JSON?
No. The converter extracts the final computed *value* of the cell (e.g., '150'), not the mathematical formula (e.g., '=SUM(A1:A5)'). All Excel logic is permanently lost during the conversion to flat JSON.
Is it safe to convert payroll data here?
Absolutely. Because the binary parsing engine runs locally via WebAssembly/JavaScript, your spreadsheet never leaves your computer. The conversion happens instantly in your RAM.