write-excel-file

Write .xlsx files in a browser or Node.js

Demo

Also check out read-excel-file for reading .xlsx files.

• Renamed the default export "write-excel-file" to "write-excel-file/browser", and it uses Web Workers now.
  • Old: import writeExcelFile from "write-excel-file"
  • New: import writeExcelFile from "write-excel-file/browser"
• The minimum required Node.js version is 18.
• Renamed cell property color to textColor.
• Removed headerStyle parameter. Pass getHeaderStyle() parameter instead.
• images[] parameter no longer accepts string values (i.e. file paths). Instead, use fs.createReadStream(filePath) function to convert file paths to Streams.

• Changed the arguments of writeExcelFile() function.

  • The following options are now passed as part of a separate (third) argument: fontFamily, fontSize, features.

• Changed the arguments of writeExcelFile() function when writing a file with mulitiple sheets.

  • Old — two arguments:
    • [data1, data2]
    • { sheets: ['Sheet1', 'Sheet2'], columns: [columns1, columns2], ... }
  • New — one argument:
    • [
      • { data: data1, sheet: 'Sheet1', columns: columns1, ... },
      • { data: data2, sheet: 'Sheet2', columns: columns2, ... }
    • ]

• Changed the result of writeExcelFile() function.

  • Instead of receiving options such as fileName or filePath or buffer: true, etc, and then adjusting the return type based on those options, it now returns an object with several async toXxx() methods.
    • Old: await writeExcelFile(data, { filePath: '/path/to/output-file.xlsx' })
    • New: await writeExcelFile(data).toFile('/path/to/output-file.xlsx')

• If you were passing span property as part of a cell object:

  • Renamed span property of a cell object to columnSpan.
    • The old name still works but is deprecated.

• If you were using schema parameter:

  • Removed schema parameter from writeExcelFile() function.
    • Instead of schema parameter, either use a new columns parameter or a new function getSheetData():
      • Using the new columns parameter (not same as schema):
        • Old: await writeExcelFile(objects, { schema })
        • New: await writeExcelFile(objects, { columns })
      • Using the new function getSheetData():
        • Old: await writeExcelFile(objects, { schema })
        • New: await writeExcelFile(getSheetData(objects, schema))
  • In a schema, column property was renamed to header.
    • Old: [{ column: 'First Name', value: (person) => person.firstName }]
    • New: [{ header: 'First Name', value: (person) => person.firstName }]
  • In a schema, header property now represents a column header cell, so it can be not just a string but also an object with a value property and any optional cell style properties.
    • This means that the header style for each different column can be specified directly in a schema entry for that column.
  • In a schema, any cell properties such as value, type, format, fontWeight, etc were moved to a nested object called cell. Specifically, this cell property is a function of two arguments — object and objectIndex — which returns an object with the aforementioned cell properties. And the value property is no longer a "getter" function, it's a regular value.
  • Previously, it used to apply the default width: 14 to type: Date columns. It no longer does that.
    • Specify the width of such columns manually in a schema.
  • Removed getHeaderStyle parameter from writeExcelFile() function.
    • Use the new header property on each column in a schema to set the style for that column's header cell.
  • Previously, it used to apply bold font to the header row by default. It no longer does that.
    • Use the new header property on each column in a schema to set the style for that column's header cell.
  • If you were using getCellStyle() option:
    • Removed getCellStyle() option. It was replaced by the new cell() property in a column definition in a schema.

• If you were using features parameter:

  • The features parameter was moved from the second argument to the third argument (in case of a file with a single sheet).
  • If you implemented file.transform property of a feature:
    • Changed the first argument of files.transform.insert() / files.transform.transform() — it's now an array with each separate sheet's options.
    • Changed the second argument of files.transform.insert() / files.transform.transform():
      • Removed multipleSheetsParameters property because now all sheets' options are separate.
      • Removed attributeValue() and textContent() properties because they can be imported directly from write-excel-file/utility subpackage.
    • Removed files.transform.parameters() function. Any sheet options are now available to any feature.
  • If you implemented files.write property of a feature:
    • Changed the first argument of files.write.files() — it's now an array with each separate sheet's options.
    • Changed the second argument of files.write.files():
      • Removed multipleSheetsParameters property because now all sheets' options are separate.
      • Removed attributeValue() and textContent() properties because they can be imported directly from write-excel-file/utility subpackage.
    • Removed files.write.parameters() function. Any sheet options are now available to any feature.

• If you were using TypeScript:

  • Renamed some TypeScript types:
    • ColumnSchema<Object, ValueType> → Column<Object>
    • Schema → Column[]
    • ValueType → Value

Install

npm install write-excel-file --save

Alternatively, it could be included on a web page directly via a <script/> tag.

Use

The default exported function creates an .xslx file from sheet data.

Sheet data must be an array of rows. Each row must be an array of cells. Each cell should be represented by a value — string, number, boolean or Date — or be null in case it's empty.

Example:

const sheetData = [
  ['A','B','C'], // 1st row
  ['x',123,true], // 2nd row
  ['y',456,false] // 3rd row
]

Output file:

| A | B | C | | - | - | - | | x | 123 | TRUE | | y | 456 | FALSE |

Code (Node.js):

import writeExcelFile from 'write-excel-file/node'

await writeExcelFile(sheetData).toFile('/path/to/output-file.xlsx')

For some data cells, it might be required to customize their appearance or output format. In that case, a cell could be represented by an object with properties:

• value — cell value
• (optional) type — cell value type; if not specified, will be derived from value
• (optional) cell options such as style properties or output format

Here's an example where "Amount" column values are displayed as US Dollar currency, and highlighted in yellow where the value exceeds $1000.

[
  ['Order ID', 'Amount'],
  [1, { value: 1234.56, format: '[$$-409]#,##0.00', backgroundColor: '#FFFF00' }],
  [2, { value: 789, format: '[$$-409]#,##0.00' }]
]

Output:

| Order ID | Amount | | - | - | | 1 | $1,234.56 | | 2 | $789.00 |

The type property of a cell object is optional because it will be automatically derived from the value property, or will default to String if the value is empty or not supported.

Possible type:

• String — type: String and value: 'Text'
• Number — type: Number and value: 123
• Boolean — type: Boolean and value: true
• Date — type: Date and value: new Date()
• 'Formula' — type: 'Formula' and value: '=AVERAGE(A1:A10)'

And while sheetData argument provides the ultimate control and flexibility, most people just need to quickly output a list of JSON objects to an .xlsx file, so there's an easy way to do so.

Import

This package provides a separate import path for each different environment, as described below.

Browser

write-excel-file/browser

Example 1: Write sheetData to a file called file.xlsx and trigger a "Save as" file dialog so that the user could save the file to their disk.

import writeExcelFile from 'write-excel-file/browser'

await writeExcelFile(sheetData).toFile('file.xlsx')

Example 2: Write sheetData to a Blob.

const blob = await writeExcelFile(sheetData).toBlob()

Node.js

write-excel-file/node

Example 1: Write sheetData to a file at path /path/to/output-file.xlsx.

import writeExcelFile from 'write-excel-file/node'

await writeExcelFile(sheetData).toFile('/path/to/output-file.xlsx')

Example 2: Write sheetData to a Buffer.

const buffer = await writeExcelFile(sheetData).toBuffer()

Example 3: Write sheetData as a readable Stream.

const readStream = await writeExcelFile(sheetData).toStream()

Example 4: Write sheetData to a writable Stream.

const writeStream = fs.createWriteStream('/path/to/output-file.xlsx')
await writeExcelFile(sheetData).toStream(writeStream)

AWS S3 might throw Cannot determine length of [object Object]:

await new AWS.S3().putObject({
  Bucket: ...,
  Key: ...,
  Body: readStream,
  ContentType: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'
}).promise()

The reason is that AWS S3 only accepts streams of known length, and the length of a .zip file can't be known in advance.

Workaround for AWS SDK v2: write sheetData to a Buffer instead of a Stream, and then pass it as Body.

Workaround for AWS SDK v3: use Upload class from @aws-sdk/lib-storage package instead of PutObjectCommand from @aws-sdk/client-s3 package.

Universal

write-excel-file/universal

This one works both in a web browser and Node.js. It can only write sheetData to a Blob, which could be a bit less convenient for general use.

import writeExcelFile from 'write-excel-file/universal'

const blob = await writeExcelFile(sheetData).toBlob()

Column Widths

One could set column widths (in "characters" rather than in "pixels") by passing columns option:

// Set Column #3 width to "20 characters".
const columns = [
  {},
  {},
  { width: 20 }, // in characters
  {}
]

await writeExcelFile(sheetData, { columns }).toFile(...)

Convert Objects To Sheet Data

Usually, there's a list of objects that should be written to an .xlsx file.

One could easily convert such objects to sheetData by passing an additional parameter called columns which should describe the list of columns in the output .xlsx file.

Each column should be an object with properties:

• (optional) header — describes the column header cell
  • Either a string or a cell object
• cell — describes each (non-header) cell in this column
  • A function of two arguments — object and objectIndex — that returns a cell object
• (optional) width — column width (in characters)

Example:

// These objects should be written to an `.xlsx` file
const objects = [
  {
    name: 'John Smith',
    dateOfBirth: new Date(Date.UTC(2000, 1 - 1, 5)),
    income: 120000,
    married: true
  },
  {
    name: 'Alice Brown',
    dateOfBirth: new Date(Date.UTC(2005, 4 - 1, 3)),
    income: 60000,
    married: false
  }
]

// These columns should be written to the `.xlsx` file
const columns = [
  {
    header: getHeader('Name'),
    cell: (person) => ({
      value: person.name
    }),
    width: 20 // `width` is optional and is measured in characters
  },
  {
    header: getHeader('Date of Birth'),
    cell: (person) => ({
      value: person.dateOfBirth,
      type: Date, // `type` is optional and will be derived from `value`
      format: 'mm/dd/yyyy'
    })
  },
  {
    header: getHeader('Income'),
    cell: (person) => ({
      value: person.income,
      type: Number, // `type` is optional and will be derived from `value`
      format: '#,##0.00'
    })
  },
  {
    header: getHeader('Married'),
    cell: (person) => ({
      value: person.married,
      type: Boolean // `type` is optional and will be derived from `value`
    })
  }
]

// Helper function: creates a header cell object
const getHeader = (text) => ({
  value: text,
  fontWeight: 'bold'
})

await writeExcelFile(objects, { columns }).toFile(...)

will write the following sheetData:

[
  [
    { value: 'Name', fontWeight: 'bold' },
    { value: 'Date of Birth', fontWeight: 'bold' },
    { value: 'Income', fontWeight: 'bold' },
    { value: 'Married', fontWeight: 'bold' }
  ],
  [
    { value: 'John Smith' },
    { value: 2000-01-05T00:00:00.000Z, type: Date, format: 'mm/dd/yyyy' },
    { value: 120000, type: Number, format: '#,##0.00' },
    { value: true, type: Boolean }
  ],
  [
    { value: 'Alice Brown' },
    { value: 2005-04-03T00:00:00.000Z, type: Date, format: 'mm/dd/yyyy' },
    { value: 60000, type: Number, format: '#,##0.00' },
    { value: false, type: Boolean }
  ]
]

Passing objects and columns is just a shortcut for first using getSheetData() function to convert objects to sheetData and then writing sheetData to an .xlsx file.

import writeExcelFile, { getSheetData } from 'write-excel-file/node'

// Convert `objects` to `sheetData`.
const sheetData = getSheetData(objects, columns)

// Write `sheetData` to an `.xslx` file.
// Also pass the `columns` here to apply the column `width`.
await writeExcelFile(sheetData, { columns }).toFile(...)

Cell Options

Each cell object could specify:

• Custom format property
• Custom style properties

Format

A custom output format could be specified for cells with type: Date, Number, String or "Formula". Its purpose is to display the "raw" cell value — for example, a number or a date — in a particular way: as a floating-point number with a specific number of decimal places, or as a percentage, or maybe as a date in a particular date format, etc.

There're many standardized formats to choose from.

Below are some of the commonly used Number formats.

• 0.00 — Floating-point number with 2 decimal places. Example: 1234.56.
• 0.000 — Floating-point number with 3 decimal places. Example: 1234.567.
• #,##0 — Number with a comma as a thousands separator, as used in most English-speaking countries. Example: 1,234,567.
• #,##0.00 — Currency, as in most English-speaking countries. Example: 1,234.50.
• 0% — Percents. Example: 30%.
• 0.00% — Percents with 2 decimal places. Example: 30.00%.

All Date cells are required to specify a format, unless a default dateFormat option has been specified.

• mm/dd/yy — US date format. Example: 12/31/00 for December 31, 2000.

• mmm d yyyy — Example: Dec 31 2000.

• d mmmm yyyy — Example: 31 December 2000.

• dd/mm/yyyy hh:mm AM/PM — US date-time format. Example: 31/12/2000 12:30 AM.

• or any other format where:

  • yy — Last two digits of a year number.
  • yyyy — Four digits of a year number.
  • m — Month number without a leading 0.
  • mm — Month number with a leading 0 (when less than 10).
  • mmm — Month name (short).
  • mmmm — Month name (long).
  • d — Day number without a leading 0.
  • dd — Day number with a leading 0 (when less than 10).
  • h — Hours without a leading 0.
  • hh — Hours with a leading 0 (when less than 10).
  • mm — Minutes with a leading 0 (when less than 10).
  • ss — Seconds with a leading 0 (when less than 10).
  • AM/PM — Either AM or PM, depending on the time.

A String cell could also specify a format.

• It could specify @ format in order to explicitly declare itself being of "Text" type rather than the default "General" type. The point is, this way Microsoft Excel won't attempt to "intelligently" interpret the String cell value as a number or a date, as it usually does by default. For example, by default, if a String cell value is "123456", Microsoft Excel will try to display it as a 123,456 number rather than a "123456" string.

Style

Cell style properties:

• Dimensions

  • height: number — Row height, in "points".

• Combine cells

  • columnSpan: number — Column span. Specifying columnSpan: N will combine a given cell with N - 1 of the next cells in the same row. Such combined cells will visually appear as a single one when viewing the spreadsheet, but in the sheetData structure those cells should still stay separate. In that case, all the cells except the first one will simply be ignored. One could use null or undefined to represent such ignored cells. For example, if the first cell in a row spans 3 columns, then the row could look like [{ value: 'Text', columnSpan: 3 }, null, null, { value: 'After text' }].

  • rowSpan: number — Row span. Specifying rowSpan: N will combine a given cell with N - 1 of the cells below it in the same column. Such combined cells will visually appear as a single one when viewing the spreadsheet, but in the sheetData structure those cells should still stay separate. In that case, all the cells except the top one will simply be ignored. One could use null or undefined to represent such ignored cells. For example, if the top left cell spans 2 rows, then the first row could look like [{ value: 'A1-A2', rowSpan: 2 }, { value: 'B1' }] and the second row could look like [null, { value: 'B2' }].

• Alignment

  • align: string — Horizontal alignment of cell content. Available values: "left", "center", "right".

  • alignVertical: string — Vertical alignment of cell content. Available values: "top", "center", "bottom".

  • textRotation: number — Text rotation angle. Values from -90 to 90 are supported. Positive values rotate the text counterclockwise, and negative values rotate the text clockwise.

  • indent: number — Horizontal indentation level for the cell content.

  • wrap: boolean — Set to true to "wrap" text when it overflows the cell.

• Font

  • fontFamily: string — Can be used to print text in a custom font family. Example: "Calibri".
  • fontSize: number — Can be used to print text in a custom font size. Example: 12.
  • fontWeight: string — Can be used to print text in bold. Available values: "bold".
  • fontStyle: string — Can be used to make text appear italicized. Available values: "italic".

• Text style

  • textColor: string — Cell text color (in hexademical format). Example: "#aabbcc".
  • textDecoration: object — Can be used to decorate text.
    • underline: boolean — Draws an underline below the text.
    • doubleUnderline: boolean — Draws a double underline below the text.
    • strikethrough: boolean — Draws a horizontal line through the middle of the text.

• Fill

  • backgroundColor: string — Cell background color (in hexademical format). Example: "#aabbcc".
  • fillPatternStyle: string — Cell fill pattern style, when a certain fill pattern should be used. Example: "lightGrid".
  • fillPatternColor: string — Cell fill pattern color (in hexademical format), when a certain fill pattern should be used. Example: "#aabbcc".

• Border

  • borderColor: string — Cell border color. Example: "#aabbcc".
  • borderStyle: string — Cell border style. Example: "thick".
    • leftBorderColor
    • leftBorderStyle
    • rightBorderColor
    • rightBorderStyle
    • topBorderColor
    • topBorderStyle
    • bottomBorderColor
    • bottomBorderStyle

Sheet Options

The following sheet-specific options could be passed as part of the second argument to writeExcelFile() function:

• sheet: string — The name of the sheet.
• columns: object[] — Column widths.
• orientation: string — Sheet orientation. Default is "portrait". Possible values: "portrait", "landscape".
• dateFormat: string — Default format that will be used for all Date cells. Example: "mm/dd/yyyy".
• stickyRowsCount: number — Makes a given number of top rows "sticky" (Excel calls them "frozen").
• stickyColumnsCount: number — Makes a given number of columns at the start "sticky" (Excel calls them "frozen").
• showGridLines: boolean — Pass false to hide grid lines.
• rightToLeft: boolean — Pass true to use right-to-left layout. This is used in right-to-left languages like Arabic.
• zoomScale: number — Initial zoom factor. For example, 1.5 would scale the sheet to 150%.

Global Options

The following options are not specific to any particular sheet and apply to the entire .xlsx file:

• fontFamily: string — Default font family for all sheets. Example: "Calibri".
• fontSize: number — Default font size for all sheets. Example: 11.
• features: Feature[] — Additional third-party "features" that may extend the functionality of this package in any custom way.

These options can be passed after any other arguments, i.e. as a third argument when writing a single-sheet file or as a second argument when writing a multi-sheet file.

Multiple Sheets

To create an .xlsx file with multiple sheets, instead of passing sheetData as the first argument and sheetOptions as the second argument, pass an array of objects of shape { data: SheetData, ...options?: SheetOptions } as the first argument.

await writeExcelFile([
  {
    data: data1,
    sheet: 'Sheet 1',
    columns: columns1,
    stickyRowsCount: 1
  },
  {
    data: data2,
    sheet: 'Sheet 2',
    columns: columns2,
    stickyColumnsCount: 1
  }
]).toFile(...)

Features

This package is quite minimal but at the same time quite extensible by providing custom "feature" implementations.

// Import a TypeScript interface called `Feature`.
import type { Feature } from 'write-excel-file/node'

// This is an implementation of a custom "feature".
// It must implement the `Feature` TypeScript interface.
const myCustomFeature: Feature = {
  ...
}

await writeExcelFile(
  data,
  { sheet: 'Sheet Name' },
  { features: [myCustomFeature] }
).toFile(...)

So what can it do?

An .xlsx file is really just a *.zip archive with the .zip file extension renamed to .xlsx. If one renames an *.xslx file to a *.zip file and unpacks it, one could see that it has a certain directory structure and contains certain *.xml files. A "feature" implementation could "hook" into creating those *.xml files — xl/styles.xml, xl/worksheets/sheet{id}.xml, etc — to transform their content in any desired way.

Sidenote: When implementing a "feature", one could use the few "helper" functions that are available for import from write-excel-file/utility subpackage (the built-in "features" use these helper functions):

• findElement(xml, 'tag') — Finds a single <tag/> element.
• findElementInsideElement(xml, 'tag', enclosingElement) — Finds a single <tag/> element inside a given element.
• getChildElements(xml, element) — Returns all child elements of a given element.
• getOpeningTagMarkup('tag', { attribute: 'value' }) — Returns XML for an opening <tag> with given attributes.
• getClosingTagMarkup('tag') — Returns XML for a closing </tag>.
• getSelfClosingTagMarkup('tag', { attribute: 'value' }) — Returns XML for a self-closing <tag/> with given attributes.
• insertElementMarkupAccordingToOrderOfSiblings(xml, elementXml, orderOfSiblings, 'parentTagName1', ...) — Inserts a given markup of a single element in a given xml string at a given "path" of parent element(s) while maintaining a pre-defined of siblings.
  • Use this function whenever inserting a new element in an .xml file. The reason is that .xlsx file format is extremely sensitive to the order of elements, and maintaining the correct order of siblings is essential to avoid a "corrupt file" error when opening the resulting file in a spreadsheet viewer application.
  • They say that the order of siblings is specified in XML "schemas" (.xsd files) in "Part 4" of the ECMA-376 Office Open XML File Formats" specification. I personally didn't even bother checking because this whole "specification" thing already looks needlessly convoluted. Anyway, I asked Google's AI for "xlsx sheet.xml elements order" and it did output some kind of a list — a slightly different one depending on the exact wording — which I used as a loose reference and it seemed to fix those pesky "corrupt file" errors, so you could do the same.
  • Example: insertElementMarkupAccordingToOrderOfSiblings(xml, '<child1/>', ['child1', 'child2', 'child3'], 'parent1') will insert <child1/> inside the first <parent1> element in the xml string.
  • Optionally, the insertion "path" could be specified in more detail by passing not just a single parent tag name but a chain of parent tag names. For example, insertElementMarkupAccordingToOrderOfSiblings(xml, '<child1/>', ['child1', 'child2', 'child3'], 'parent1', 'parent2') will insert <child1/> inside the first <parent1> element of the first <parent2> element in the xml string.
• getOrderOfSiblings(fileName, 'parentTagName1', ...) — One could use it to get the orderOfSiblings argument for insertElementMarkupAccordingToOrderOfSiblings() function.
  • The list of file names or tag names supported by this function is nowhere near complete, so don't rely on it too much. Currently, it only supports 3 file names, and only the top-level tags in those files.
• replaceElement(xml, element, replacementXml) — Replaces element with a given substring.
• getMarkupInsideElement(xml, element) — Returns the XML inside a given element.
• setMarkupInsideElement(xml, element, replacementXml) — Replaces the XML inside a given element.
• prependMarkupInsideElement(xml, element, addedXml) — Prepends XML inside a given element.
• appendMarkupInsideElement(xml, element, addedXml) — Appends XML inside a given element.
• sanitizeAttributeName('attribute') — "Sanitizes" a string for output as an attribute name. Removes any illegal characters. Escapes any "special" characters.
• sanitizeAttributeValue('value') — "Sanitizes" a string for output as an attribute value. Removes any illegal characters. Escapes any "special" characters.
• sanitizeTextContent('text') — "Sanitizes" a string for output as text content of an XML element. Removes any illegal characters. Escapes any "special" characters.

For an example of a "feature" implementation see ./source/xlsx/features directory of the code repository. Also see the definition of the Feature TypeScript interface in ./index.d.ts file and also see ./types/features directory for TypeScript definitions of the built-in "features". Also, see an example that adds a "sensitivity label" feature.

P.S. When implementing a "feature", don't rely too much on the .xlsx file contents to have any particular shape or form (within reason). For example, don't really assume the XML markup in those files to have a certain fixed shape or to maintain a particular fixed order of elements or their attributes. That's because in future versions of this package, the XML markup inside those .xml files may potentially be refactored, with some elements considered "unnecessary" and being removed, or non-previously-existing elements being added by default. This means that transform functions shouldn't rely on a particular order of existing elements or attributes to find-and-replace those, nor should they presume any particular elements or attributes to not already exist when adding those, i.e. perhaps they should check before adding, in which case perhaps prefer using transform over insert (see stickyRowsOrColumns feature code for an example). Analogous, files.write functions could use read() function to check if a file with such name already exists. And to avoid any potential conflicts when introducing a new "relationship ID", consider using a unique "namespace" so that it looks like rId-${namespace}-1 rather than just rId1.

P.P.S. Also note that the .xlsx document specification (officially called "ECMA-376 Office Open XML File Formats") dictates a specific order of each and every XML element, and breaking that order will result in a "corrupt file" error when opening the file in a spreadsheet viewer application.

Images

An .xlsx file could include images. Images reside in their own layer above any other data in a sheet. Each separate sheet has its own separate layer of images.

const images = [
  { width: 100, ... },
  { width: 200, ... }
]

await writeExcelFile(sheetData, { images }).toFile(...)

An image object should have properties:

• content — Image content.
  • Browser: File or Blob or ArrayBuffer.
  • Node: Readable Stream or Buffer or Blob.
• contentType — MIME content type of the image. Example: "image/jpeg".
• width — Image width, in pixels.
• height — Image height, in pixels.
• dpi — Image "DPI" (aka "dots per inch").
  • For legacy reasons described in the document, images in XLSX documents are measured not pixels but in some other weird measurement units. Mapping image pixels to those weird measurement units requires knowing a "DPI" of an image.
  • The usual "DPI" of an image is either 72 or 96. Both values are equally meaningless. Pick one or the other.
  • To find out an image's DPI in Windows, open file "Properties" and go to "Details" tab. There, it will say "Horizontal resolution" and "Vertical resolution".
  • If, after writing an .xlsx file, an image looks too large then try specifying a higher DPI. Conversely, if an image looks too small then try specifying a lower DPI.
• anchor — The cell that the image is positioned against. In other words, the image's top left corner is tied to the anchor cell's top left corner.
  • row — Cell row number, starting with 1.
  • column — Cell column number, starting with 1.
• offsetX — (optional) Image horizontal offset, in pixels, relative to the anchor cell.
• offsetY — (optional) Image vertical offset, in pixels, relative to the anchor cell.
• title — (optional) Image title.
• description — (optional) Image description.

Conditional Formatting

Conditional Formatting is an .xlsx standard feature that applies a given style to cells that meet a certain condition.

// An example of one conditional formatting rule
const conditionalFormatting = [{
  cellRange: {
    from: {
      row: 2,
      column: 1
    },
    to: {
      row: 3,
      column: 1
    }
  },
  condition: {
    operator: '>',
    value: 100
  },
  style: {
    backgroundColor: '#cc0000'
  }
}]

await writeExcelFile(sheetData, { conditionalFormatting }).toFile(...)

A conditional formatting rule is defined by properties:

• cells — An object specifying a cell range that the rule could be applied to, i.e. it limits the bounds of the rule.
  • from — Top-left cell
  • to — Bottom-right cell
  • Each cell is defined by:
    • row — Row number (starting from 1)
    • column — Column number (starting from 1)
• condition — An object specifying a condition that has to be met in order for the rule to be applied to a given cell.
  • Matching a cell by its value:
    • Compare to a single value:
      • { operator: '<', value: 100 } — Matches any cells having a numeric value less than 100.
    • Compare to two values — value and value2:
      • { operator: '...', value: 100, value2: 200 } — Matches any cells having a numeric value between 100 and 200 (inclusive).
    • Available operators: <, >, <=, >=, =, !=, ...
  • Matching an entire row by a formula:
    • { formula: '=$A1="ERROR"' } — Matches all rows having text ERROR in column A.
      • This dollar-sign technique is called "Mixed Reference with Fixed Column".
• style — An object specifying the cell style to apply to matching cells.
  • Supports a subset of cell style properties:
    • Font weight
    • Font style
    • Text decoration
    • Text color
    • Background color
    • Fill
    • Border

P.S. When viewing a spreadsheet, if multiple conditional formatting rules "conflict" over the same cell, only the first rule to match the condition will be applied to that cell.

Browser Support

An .xlsx file is just a .zip archive with an .xslx file extension. This package uses fflate for .zip compression. See fflate's browser support for further details.

CDN

To include this library directly via a <script/> tag on a page, one can use any npm CDN service, e.g. unpkg.com or jsdelivr.com

<script src="https://unpkg.com/[email protected]/bundle/write-excel-file.min.js"></script>

<script>
  writeXlsxFile(data, { fileName: 'file.xlsx' })
</script>

GitHub

On March 9th, 2020, GitHub, Inc. silently banned my account (erasing all my repos, issues and comments, even in my employer's private repos) without any notice or explanation. Because of that, all source codes had to be promptly moved to GitLab. The GitHub repo is now only used as a backup (you can star the repo there too), and the primary repo is now the GitLab one. Issues can be reported in any repo.

License

MIT