Schema Builder

Dynamic Styles

Compute export-time styles from the source row when styling depends on known data.

Pass a function to style when formatting depends on the source row at export time.

The function receives:

row
rowIndex
subRowIndex

This is the right model when JavaScript already knows the information needed to choose the style.

Row-dependent styling

import { createExcelSchema
 } from "@chronicstone/typed-xlsx";

type Order
 = {
  status
: "paid" | "pending" | "overdue";
  amount
: number;
};

const statusColors
: Record
<Order
["status"], string> = {
  paid
: "166534",
  pending
: "A16207",
  overdue
: "B42318",
};

const schema
 = createExcelSchema
<Order
>()
  .column
("status", {
    accessor
: "status",
    style
: (row
) => ({
      font
: {
        bold
: row
.status
 === "overdue",
        color
: { rgb
: statusColors
[row
.status
] },
      },
      fill
: {
        color
: { rgb
: row
.status
 === "overdue" ? "FEF2F2" : "FFFFFF" },
      },
    }),
  })
  .column
("amount", {
    accessor
: "amount",
    style
: (row
) => ({
      numFmt
: "$#,##0.00",
      font
: { bold
: row
.status
 === "overdue" },
    }),
  })
  .build
();

Sub-row-aware styling

When an accessor expands into sub-rows, subRowIndex lets the style function align with the physical row being emitted.

import { createExcelSchema
 } from "@chronicstone/typed-xlsx";

type Order
 = {
  items
: Array
<{ qty
: number; fulfilled
: boolean; unitPrice
: number }>;
};

const schema
 = createExcelSchema
<Order
>()
  .column
("qty", {
    accessor
: (row
) => row
.items
.map
((item
) => item
.qty
),
  })
  .column
("lineTotal", {
    accessor
: (row
) => row
.items
.map
((item
) => item
.qty
 * item
.unitPrice
),
    style
: (row
, _rowIndex
, subRowIndex
) => {
      const item
 = row
.items
[subRowIndex
];
      return {
        numFmt
: "$#,##0.00",
        font
: {
          color
: { rgb
: item
?.fulfilled
 ? "166534" : "B42318" },
        },
      };
    },
  })
  .build
();

Use dynamic styles when

Use style: (row) => ... when:

the styling decision is already known during export
you want full JavaScript freedom
the workbook does not need to keep reevaluating the style after open

If the style should remain live in Excel and react to formulas or user edits, use Conditional Styles instead.

Base Styles

Apply stable export-time CellStyle objects to data cells and headers.

Conditional Styles

Apply native Excel conditional formatting with the same formula DSL used by formula columns.