docs.sheetjs.com/docz/docs/07-csf/07-features/06-nf.md

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Number Formats

File Format Support (click to show)

Modern applications separate "content" from "presentation". A value like $3.50 is typically stored as the underlying value (3.50) with a format ($0.00). Parsers are expected to render values using the respective number formats.

Text-based file formats like CSV and HTML mix content and presentation. $3.50 is stored as the formatted value. The formatted values can be generated from many different values and number formats. SheetJS parsers expose options to control value parsing and number format speculation.

Formats	Basic	Storage Representation
XLSX / XLSM	✔	Number Format Code
XLSB	✔	Number Format Code
XLS	✔	Number Format Code
XLML	✔	Number Format Code
SYLK	R	Number Format Code
ODS / FODS / UOS	✔	XML Tokens
NUMBERS		Binary encoding
WK1	+	Fixed set of formats
WK3 / WK4		Binary encoding
WKS Lotus	+	Fixed set of formats
WKS Works	+	Fixed set of formats
WQ1	+	Fixed set of formats
WQ2		Binary encoding
WB1 / WB2 / WB3		Binary encoding
QPW	+	Binary encoding
DBF		Implied by field types
HTML	!	Special override
CSV	*	N/A
PRN	*	N/A
DIF	*	N/A
RTF	*	N/A

(+) mark formats with limited support. The QPW (Quattro Pro Workbooks) parser supports the built-in date and built-in time formats but does not support custom number formats. Date and Time support in modern Excel formats requires limited number format support to distinguish date or time codes from standard numeric data.

Asterisks (*) mark formats that mix content and presentation. Writers will use formatted values if cell objects include formatted text or number formats. Parsers may guess number formats for special values.

The letter R (R) marks features parsed but not written in the format.

(!) HTML mixes content and presentation. The HTML DOM parser supports special attributes to override number formats

This example generates a worksheet with common number formats. sheet_to_html uses the number formats in generating the HTML table. The "Export" button generates workbooks with number formatting.

function SheetJSSimpleNF(props) {
  const [ws, setWS] = React.useState();
  const fmt = React.useRef(null);

  /* when the page is loaded, create worksheet and show table */
  React.useEffect(() => {
    /* Create worksheet from simple data */
    const ws = XLSX.utils.aoa_to_sheet([
      ["General",   54337      ],
      ["Currency",      3.5    ],
      ["Thousands",  7262      ],
      ["Percent",       0.0219 ],
    ]);

    /* assign number formats */
    ws["B2"].z = '"$"#,##0.00_);\\("$"#,##0.00\\)';
    ws["B3"].z = '#,##0';
    ws["B4"].z = "0.00%";

    setWS(ws);
  }, []);

  const xport = (fmt) => {
    /* Export to file (start a download) */
    const wb = XLSX.utils.book_new();
    XLSX.utils.book_append_sheet(wb, ws, "Formats");
    XLSX.writeFile(wb, `SheetJSSimpleNF.${fmt}`);
  };

  const fmts = ["xlsx", "xls", "csv", "xlsb", "html", "ods"];
  return ( <>
    <select ref={fmt}>{fmts.map(fmt => (<option value={fmt}>{fmt}</option>))}</select>
    <button onClick={()=>xport(fmt.current.value)}><b>Export!</b></button>
    <div dangerouslySetInnerHTML={{__html: ws && XLSX.utils.sheet_to_html(ws) || "" }}/>
  </> );
}

Values and Formatting

Typically spreadsheets will include formatted text such as currencies ($3.50) or large numbers with thousands separators (7,262) or percentages (2.19%).

To simplify editing, the applications will store the underlying values and the number formats separately. For example, $3.50 will be represented as the value 3.5 with a number format that mandates a $ sigil and 2 decimal places.

CSV and other formats only support the formatted text. Applications reading CSV files are expected to interpret the values as numbers or dates.

Dates and Times

Many spreadsheet formats store dates and times using a number that represents the number of seconds or days after some epoch. Dates are covered in more detail in the dedicated section.

Percentages

Percentage formats automatically scale values by 100. Multiple percent symbols repeat the effect. For example, a cell with value 2.19% is typically stored as a numeric cell with value 0.0219 and number format 0.00%

The following table uses the en-US locale (. as the decimal point symbol):

Number	Format	en-US Text
0.0219	0.00%	2.19%
2.19	0.00%	219%
0.0219	0.00%%	219%%
2.19	0.00%%	21900%%

SheetJS Representation

Number formats and values are attached to cells. The following keys are used:

Key	Description
v	raw value (number, string, Date object, boolean)
z	number format string associated with the cell (if requested)
w	formatted text (if applicable)

The cell.w formatted text for each cell is produced from cell.v and cell.z format. If the format is not specified, the Excel General format is used.

By default, parsers do not attach number formats to cells. The cellNF option instructs XLSX.read or XLSX.readFile to save the formats.

Number Format Strings

The z format string follows the Excel persistence rules as described in ECMA-376 18.8.31 (Number Formats). For more info, see the Excel documentation article Create or delete a custom number format

The rules are slightly different from how Excel displays custom number formats. In particular, literal characters must be wrapped in double quotes or preceded by a backslash.

The following example prints number formats from a user-specified file:

function SheetJSExtractNF(props) {
  const [rows, setRows] = React.useState([])

  return ( <>
    <input type="file" onChange={async(e) => {
      /* parse workbook with cellNF: true */
      const wb = XLSX.read(await e.target.files[0].arrayBuffer(), {cellNF: true});

      /* look at each cell in each worksheet */
      const formats = {};
      wb.SheetNames.forEach(n => {
        var ws = wb.Sheets[n]; if(!ws || !ws["!ref"]) return;
        var ref = XLSX.utils.decode_range(ws["!ref"]);
        for(var R = 0; R <= ref.e.r; ++R) for(var C = 0; C <= ref.e.c; ++C) {
          var addr = XLSX.utils.encode_cell({r:R,c:C});
          if(!ws[addr] || !ws[addr].z || formats[ws[addr].z]) continue;
          /* when a new format is found, save the address */
          formats[ws[addr].z] = `'${n}'!${addr}`;
          setRows(Object.entries(formats));
        }
      });
    }}/>
    <table><tr><th>Format</th><th>JSON</th><th>Example Cell</th></tr>
    {rows.map((r,R) => ( <tr key={R}>
      <td><code>{r[0]}</code></td>
      <td><code>{JSON.stringify(r[0])}</code></td>
      <td>{r[1]}</td>
    </tr> ))}
    </table>
  </> );
}

Miscellany

The default formats are listed in ECMA-376 18.8.30:

Default Number Formats (click to show)

ID	Format
0	General
1	0
2	0.00
3	#,##0
4	#,##0.00
9	0%
10	0.00%
11	0.00E+00
12	# ?/?
13	# ??/??
14	m/d/yy (see below)
15	d-mmm-yy
16	d-mmm
17	mmm-yy
18	h:mm AM/PM
19	h:mm:ss AM/PM
20	h:mm
21	h:mm:ss
22	m/d/yy h:mm
37	#,##0 ;(#,##0)
38	#,##0 ;[Red](#,##0)
39	#,##0.00;(#,##0.00)
40	#,##0.00;[Red](#,##0.00)
45	mm:ss
46	[h]:mm:ss
47	mmss.0
48	##0.0E+0
49	@

Format 14 (m/d/yy) is localized by Excel: even though the file specifies that number format, it will be drawn differently based on system settings. It makes sense when the producer and consumer of files are in the same locale, but that is not always the case over the Internet. To get around this ambiguity, parse functions accept the dateNF option to override the interpretation of that specific format string.

Excel Format Categories

Excel officially recognizes a small number of formats as "Currency" and another set of formats as "Accounting". The exact formats in en-US are listed below:

Currency

JS String	Decimal Places	Negative Color
'"$"#,##0_);\\("$"#,##0\\)'	0	Black
'"$"#,##0_);[Red]\\("$"#,##0\\)'	0	Red
'"$"#,##0.00_);\\("$"#,##0.00\\)'	2	Black
'"$"#,##0.00_);[Red]\\("$"#,##0.00\\)'	2	Red

Accounting

JS String	Decimal	Sigil
'_(* #,##0_);_(* \\(#,##0\\);_(* "-"_);_(@_)'	0
'_("$"* #,##0_);_("$"* \\(#,##0\\);_("$"* "-"_);_(@_)'	0	$
'_(* #,##0.00_);_(* \\(#,##0.00\\);_(* "-"??_);_(@_)'	2
'_("$"* #,##0.00_);_("$"* \\(#,##0.00\\);_("$"* "-"??_);_(@_)'	2	$

For other locales, the formats can be discovered by creating a file with the desired format and testing with the Number Format Strings demo

HTML Override

This feature is discussed in the HTML utilities section