docs.sheetjs.com/docz/docs/07-csf/03-sheet.md

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Sheet Objects	3

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Excel supports 4 different types of "sheets":

• "worksheets": normal sheets
• "chartsheets": full-tab charts
• "macrosheets": legacy (pre-VBA) macros
• "dialogsheets": legacy (pre-VBA) dialog windows

Generic Sheet Object

Generic sheets are plain JavaScript objects. Each key that does not start with ! is an A1-style address whose corresponding value is a cell object.

Worksheet Range

The !ref property stores the A1-style range.

Functions that work with sheets should use this property to determine the range. Cells that are assigned outside of the range are not processed.

For example, in the following sparse worksheet, the cell A3 will be ignored since it is outside of the worksheet range (A1:B2):

var ws = {
  // worksheet range is A1:B2
  "!ref": "A1:B2",

  // A1 is in the range and will be included
  "A1": { t: "s", v: "SheetJS" },

  // cell A3 is outside of the range and will be ignored
  "A3": { t: "n", v: 5433795 },
};

Utility functions and functions that handle sheets should test for the presence of the !ref field. If the !ref is omitted or is not a valid range, functions should treat the sheet as empty.

Cell Storage

By default, the parsers and utility functions generate "sparse-mode" worksheets. For a given A1-style address, sheet[ref] is the corresponding cell object.

Dense Mode

When the option dense: true is passed, parsers will generate a "dense-mode" worksheet where cells are stored in an array of arrays. sheet["!data"][R][C] returns the cell object at row R and column C (zero-indexed values).

When processing small worksheets in older environments, sparse worksheets are more efficient than dense worksheets. In newer browsers, when dealing with very large worksheets, dense sheets use less memory and tend to be more efficient.

Migrating to Dense Mode (click to show)

read, readFile, write, writeFile, and the various API functions support sparse and dense worksheets. Functions that accept worksheet or workbook objects (e.g. writeFile and sheet_to_json) will detect dense sheets.

The option dense: true should be used when creating worksheet or book objects.

Update code that manually searches for cells (adding dense mode support):

Addressing Cells

-var cell = sheet["B7"];
+var cell = sheet["!data"] != null ? (sheet["!data"][6]||[])[1] : sheet["B3"];

-var cell = sheet["B7"];
+var cell = sheet["!data"] != null ? sheet["!data"]?.[6]?.[1] : sheet["B3"];

The row and column can be calculated using XLSX.utils.decode_cell:

 var addr = "B7";
-var cell = sheet[addr];
+var _addr = XLSX.utils.decode_cell(addr);
+var cell = sheet["!data"] != null ? sheet["!data"]?.[_addr.r]?.[_addr.c] : sheet[addr];

XLSX.utils.encode_cell will be using the desired row and column indices:

-var cell = sheet[XLSX.utils.encode_cell({r:R, c:C})];
+var cell = sheet["!data"] != null ? sheet["!data"]?.[R]?.[C] : sheet[XLSX.utils.encode_cell({r:R, c:C})];

Looping across a Worksheet

Code that manually loops over worksheet objects should test for "!data" key:

const { decode_range, encode_cell } = XLSX.utils;

function log_all_cells(ws) {
  var range = decode_range(ws["!ref"]);
  // highlight-next-line
  var dense = ws["!data"] != null; // test if sheet is dense
  for(var R = 0; R <= range.e.r; ++R) {
    for(var C = 0; C <= range.e.c; ++C) {
      // highlight-next-line
      var cell = dense ? ws["!data"]?.[R]?.[C] : ws[encode_cell({r:R, c:C})];
      console.log(R, C, cell);
    }
  }
}

Update workbook and worksheet generation code

read

-var workbook = XLSX.read(data, {...opts});
+var workbook = XLSX.read(data, {...opts, dense: true});

readFile

-var workbook = XLSX.readFile(data, {...opts});
+var workbook = XLSX.readFile(data, {...opts, dense: true});

aoa_to_sheet

-var sheet = XLSX.utils.aoa_to_sheet([[1,2,3],[4,5,6]], {...opts});
+var sheet = XLSX.utils.aoa_to_sheet([[1,2,3],[4,5,6]], {...opts, dense: true});

json_to_sheet

-var sheet = XLSX.utils.json_to_sheet([{x:1,y:2}], {...opts});
+var sheet = XLSX.utils.json_to_sheet([{x:1,y:2}], {...opts, dense: true});

Sheet Properties

Each key starts with !. The properties are accessible as sheet[key].

• sheet['!ref']: A1-style sheet range string

• sheet['!margins']: Object representing the page margins. The default values follow Excel's "normal" preset. Excel also has a "wide" and a "narrow" preset but they are stored as raw measurements. The main properties are listed below:

Page margin details (click to show)

key	description	"normal"	"wide"	"narrow"
left	left margin (inches)	0.7	1.0	0.25
right	right margin (inches)	0.7	1.0	0.25
top	top margin (inches)	0.75	1.0	0.75
bottom	bottom margin (inches)	0.75	1.0	0.75
header	header margin (inches)	0.3	0.5	0.3
footer	footer margin (inches)	0.3	0.5	0.3

/* Set worksheet sheet to "normal" */
ws["!margins"]={left:0.7, right:0.7, top:0.75,bottom:0.75,header:0.3,footer:0.3}
/* Set worksheet sheet to "wide" */
ws["!margins"]={left:1.0, right:1.0, top:1.0, bottom:1.0, header:0.5,footer:0.5}
/* Set worksheet sheet to "narrow" */
ws["!margins"]={left:0.25,right:0.25,top:0.75,bottom:0.75,header:0.3,footer:0.3}

Worksheet Object

In addition to the aforementioned sheet keys, worksheets also add:

• ws['!cols']: array of column objects. Each column object encodes properties including level, width and visibility.

• ws['!rows']: array of row objects. Each row object encodes properties including level, height and visibility.

• ws['!merges']: array of merge ranges. Each merge object is a range object that represents the covered range.

• ws['!outline']: configure how outlines should behave. Options default to the default settings in Excel 2019:

key	Excel feature	default
above	Disable "Summary rows below detail"	false
left	Disable "Summary rows to the right of detail"	false

• ws['!protect']: object of write sheet protection properties. The password key specifies the password for formats that support password-protected sheets (XLSX/XLSB/XLS). The writer uses the XOR obfuscation method. The following keys control the sheet protection -- set to false to enable a feature when sheet is locked or set to true to disable a feature:

Worksheet Protection Details (click to show)

key	feature (true=disabled / false=enabled)	default
selectLockedCells	Select locked cells	enabled
selectUnlockedCells	Select unlocked cells	enabled
formatCells	Format cells	disabled
formatColumns	Format columns	disabled
formatRows	Format rows	disabled
insertColumns	Insert columns	disabled
insertRows	Insert rows	disabled
insertHyperlinks	Insert hyperlinks	disabled
deleteColumns	Delete columns	disabled
deleteRows	Delete rows	disabled
sort	Sort	disabled
autoFilter	Filter	disabled
pivotTables	Use PivotTable reports	disabled
objects	Edit objects	enabled
scenarios	Edit scenarios	enabled

• ws['!autofilter']: AutoFilter object following the schema:

type AutoFilter = {
  ref:string; // A-1 based range representing the AutoFilter table range
}

Other Sheet Types

Chartsheet Object

Chartsheets are represented as standard sheets. They are distinguished with the !type property set to "chart".

The underlying data and !ref refer to the cached data in the chartsheet. The first row of the chartsheet is the underlying header.

Macrosheet Object

Macrosheets are represented as standard sheets. They are distinguished with the !type property set to "macro".

Dialogsheet Object

Dialogsheets are represented as standard sheets. They are distinguished with the !type property set to "dialog".