Styles

XLSX uses an index-based style system. When you apply a style to a cell, the library automatically deduplicates and registers it.

#Font Styles

JSON

{
  "worksheets": [
    {
      "name": "Sheet1",
      "rows": [
        {
          "cells": [
            { "value": "Bold" },
            {
              "value": "Styled",
              "style": {
                "font": {
                  "bold": true,
                  "italic": true,
                  "size": 14,
                  "color": { "rgb": "FFFF0000" },
                  "font": "Arial"
                }
              }
            }
          ]
        }
      ]
    }
  ]
}

TypeScript

{
  cells: [
    { value: "Bold", style: { font: { bold: true } } },
    { value: "Styled", style: { font: { bold: true, italic: true, size: 14, color: { rgb: "FFFF0000" }, font: "Arial" } } },
  ],
}

#Fill Styles

JSON

{
  "worksheets": [
    {
      "name": "Sheet1",
      "rows": [
        {
          "cells": [
            {
              "value": "Yellow",
              "style": { "fill": { "foregroundColor": { "rgb": "FFFFFF00" } } }
            },
            { "value": "Blue", "style": { "fill": { "foregroundColor": { "rgb": "FF4472C4" } } } }
          ]
        }
      ]
    }
  ]
}

TypeScript

{
  cells: [
    { value: "Yellow", style: { fill: { foregroundColor: { rgb: "FFFFFF00" } } } },
    { value: "Blue", style: { fill: { foregroundColor: { rgb: "FF4472C4" } } } },
  ],
}

#Border Styles

JSON

{
  "worksheets": [
    {
      "name": "Sheet1",
      "rows": [
        {
          "cells": [
            {
              "value": "Bordered",
              "style": {
                "border": {
                  "top": { "style": "thin", "color": { "rgb": "FF000000" } },
                  "bottom": { "style": "thin", "color": { "rgb": "FF000000" } },
                  "left": { "style": "thin", "color": { "rgb": "FF000000" } },
                  "right": { "style": "thin", "color": { "rgb": "FF000000" } }
                }
              }
            }
          ]
        }
      ]
    }
  ]
}

TypeScript

{
  value: "Bordered",
  style: {
    border: {
      top: { style: "thin", color: { rgb: "FF000000" } },
      bottom: { style: "thin", color: { rgb: "FF000000" } },
      left: { style: "thin", color: { rgb: "FF000000" } },
      right: { style: "thin", color: { rgb: "FF000000" } },
    },
  },
}

Border styles: thin, medium, thick, dotted, dashed, double, hair, mediumDashed, dashDot, mediumDashDot, dashDotDot, mediumDashDotDot, slantDashDot, none.

#Alignment

JSON

{
  "worksheets": [
    {
      "name": "Sheet1",
      "rows": [
        {
          "cells": [
            {
              "value": "Centered",
              "style": {
                "alignment": { "horizontal": "center", "vertical": "center", "wrapText": true }
              }
            }
          ]
        }
      ]
    }
  ]
}

TypeScript

{
  value: "Centered",
  style: {
    alignment: { horizontal: "center", vertical: "center", wrapText: true },
  },
}

#Combining Styles

Styles are combined and deduplicated automatically:

JSON

{
  "worksheets": [
    {
      "name": "Sheet1",
      "rows": [
        {
          "cells": [
            {
              "value": "Name",
              "style": {
                "font": { "bold": true, "color": { "rgb": "FFFFFFFF" } },
                "fill": { "foregroundColor": { "rgb": "FF4472C4" } },
                "alignment": { "horizontal": "center" }
              }
            },
            {
              "value": "Score",
              "style": {
                "font": { "bold": true, "color": { "rgb": "FFFFFFFF" } },
                "fill": { "foregroundColor": { "rgb": "FF4472C4" } },
                "alignment": { "horizontal": "center" }
              }
            }
          ]
        },
        { "cells": [{ "value": "Alice" }, { "value": 95 }] }
      ]
    }
  ]
}

TypeScript

const headerStyle = {
  font: { bold: true, color: { rgb: "FFFFFFFF" } },
  fill: { foregroundColor: { rgb: "FF4472C4" } },
  alignment: { horizontal: "center" },
};

{
  cells: [
    { value: "Name", style: headerStyle },
    { value: "Score", style: headerStyle },
  ],
}

Repeated use of the same style object reuses the same cellXf index — no unnecessary duplication in the output file.

#Font Options Reference

Option	Type	Description
`bold`	`boolean`	Bold formatting
`italic`	`boolean`	Italic formatting
`underline`	`boolean`	Underline
`strike`	`boolean`	Strikethrough
`size`	`number`	Font size in points
`color`	`ColorOptions`	Spreadsheet color (CT_Color): `rgb` ARGB hex, `theme`, `tint`, `indexed` or `auto`
`font`	`string`	Font family name

#Border Options Reference

Option	Type	Description
`style`	`string`	`thin`, `medium`, `thick`, `dotted`, `dashed`, etc.
`color`	`ColorOptions`	CT_Color (`rgb` ARGB / `theme` / `tint` / `indexed` / `auto`)

#Alignment Options Reference

Option	Type	Description
`horizontal`	`string`	`general`, `left`, `center`, `right`, `fill`, `justify`, `centerContinuous`, `distributed`
`vertical`	`string`	`top`, `center`, `bottom`, `justify`, `distributed`
`wrapText`	`boolean`	Wrap text within cell
`textRotation`	`number`	Text rotation in degrees
`indent`	`number`	Indent level