exceljs

What is exceljs?

The exceljs npm package is a comprehensive library for reading, writing, and manipulating Excel files in various formats such as XLSX, CSV, and more. It provides a wide range of functionalities to work with Excel documents programmatically, including creating new sheets, styling cells, adding formulas, and handling large datasets efficiently.

What are exceljs's main functionalities?

Reading Excel Files

This feature allows you to read existing Excel files. You can iterate through rows and cells, access values, and perform operations based on the data.

{"const ExcelJS = require('exceljs');
const workbook = new ExcelJS.Workbook();
workbook.xlsx.readFile('path/to/file.xlsx')
  .then(() => {
    const worksheet = workbook.getWorksheet('Sheet1');
    worksheet.eachRow({ includeEmpty: true }, (row, rowNumber) => {
      console.log('Row ' + rowNumber + ' = ' + JSON.stringify(row.values));
    });
  });"}

Writing Excel Files

This feature enables you to create new Excel files or modify existing ones. You can add worksheets, rows, and cells with data, and save the file to the disk.

{"const ExcelJS = require('exceljs');
const workbook = new ExcelJS.Workbook();
const sheet = workbook.addWorksheet('My Sheet');
sheet.addRow(['Name', 'Profession']);
sheet.addRow(['John Doe', 'Developer']);
workbook.xlsx.writeFile('path/to/newfile.xlsx');"}

Styling Cells

This feature allows you to apply various styles to cells, such as fonts, colors, borders, and fills. It helps in making the data more readable and visually appealing.

{"const ExcelJS = require('exceljs');
const workbook = new ExcelJS.Workbook();
const sheet = workbook.addWorksheet('My Sheet');
const row = sheet.addRow(['Name', 'Profession']);
row.getCell(1).font = { bold: true };
row.getCell(2).fill = {
  type: 'pattern',
  pattern: 'solid',
  fgColor: { argb: 'FFFF0000' }
};
workbook.xlsx.writeFile('path/to/styledfile.xlsx');"}

Adding Formulas

This feature lets you insert formulas into cells. You can also pre-calculate the result of the formula and store it in the cell.

{"const ExcelJS = require('exceljs');
const workbook = new ExcelJS.Workbook();
const sheet = workbook.addWorksheet('My Sheet');
const row = sheet.addRow([100, 200, { formula: 'A1+B1', result: 300 }]);
workbook.xlsx.writeFile('path/to/formulafile.xlsx');"}

Handling Large Data Sets

This feature is particularly useful for handling large datasets without running out of memory. It streams the data to the file system as it's being processed.

{"const ExcelJS = require('exceljs');
const workbook = new ExcelJS.stream.xlsx.WorkbookWriter({ filename: 'path/to/largefile.xlsx' });
const sheet = workbook.addWorksheet('My Sheet');
for (let i = 0; i < 1000000; i++) {
  sheet.addRow(['Row ' + i, 'Data']);
}
workbook.commit();"}

Other packages similar to exceljs

xlsx

The 'xlsx' package is another popular library for parsing and writing various spreadsheet formats. It is known for its simplicity and small bundle size, but it may not offer as many features for styling and manipulating data as exceljs.

sheetjs

SheetJS, also known as 'xlsx', is a powerful and comprehensive library that supports a wide range of spreadsheet formats. It is similar to exceljs in functionality but differs in API design and implementation details.

node-xlsx

The 'node-xlsx' package is a simpler alternative for parsing and building XLSX/CSV files. It focuses on basic functionality and is easier to use for simple tasks, but lacks the advanced features and fine control provided by exceljs.

README

ExcelJS

Read, manipulate and write spreadsheet data and styles to XLSX and JSON.

Reverse engineered from Excel spreadsheet files as a project.

Installation

npm install exceljs

New Features!

• Bug Fixes
  • Now handles 10 or more worksheets in one workbook
  • theme1.xml file properly added and referenced
• Cell Borders

Coming Soon

• Column and Row Styles
• Fills

Contents

• Interface
  • Create a Workbook
  • Add a Worksheet
  • Access Worksheets
  • Columns
  • Rows
  • Handling Individual Cells
  • Merged Cells
  • Cell Styles
    • Number Formats
    • Fonts
    • Alignment
  • Reading XLSX
  • Writing XLSX
• Value Types
• Release History

Interface

var Excel = require("exceljs");

Create a Workbook

var workbook = new Excel.Workbook();

Add a Worksheet

var sheet = workbook.addWorksheet("My Sheet");

Access Worksheets

// Iterate over all sheets
// Note: workbook.worksheets.forEach will still work but this is better
workbook.eachSheet(function(worksheet, sheetId) {
    // ...
});

// fetch sheet by name
var worksheet = workbook.getWorksheet("My Sheet");

// fetch sheet by id
var worksheet = workbook.getWorksheet(1);

Columns

// Add column headers and define column keys and widths
// Note: these column structures are a workbook-building convenience only,
// apart from the column width, they will not be fully persisted.
worksheet.columns = [
    { header: "Id", key: "id", width: 10 },
    { header: "Name", key: "name", width: 32 },
    { header: "D.O.B.", key: "DOB", width: 10 }
];

// Access an individual columns by key, letter and 1-based column number
var idCol = worksheet.getColumn("id");
var nameCol = worksheet.getColumn("B");
var dobCol = worksheet.getColumn(3);
    
// set column properties
dobCol.header = "Date of Birth"; // Note: will overwrite cell value C1
dobCol.header = ["Date of Birth", "A.K.A. D.O.B."]; // Note: this will overwrite cell values C1:C2
dobCol.key = "dob"; // from this point on, this column will be indexed by "dob" and not "DOB"
dobCol.width = 15;

Rows

// Add a couple of Rows by key-value, after the last current row, using the column keys
worksheet.addRow({id: 1, name: "John Doe", dob: new Date(1970,1,1)});
worksheet.addRow({id: 2, name: "Jane Doe", dob: new Date(1965,1,7)});

// Add a row by contiguous Array (assign to columns A, B & C)
worksheet.addRow([3, "Sam", new Date()]);

// Add a row by sparse Array (assign to columns A, E & I)
var rowValues = [];
rowValues[1] = 4;
rowValues[5] = "Kyle";
rowValues[9] = new Date();
worksheet.addRow(rowValues);

// Get a row object. If it doesn't already exist, a new empty one will be returned
var row = worksheet.getRow(5);

// Set a specific row height
row.height = 42.5;

row.getCell(1).value = 5; // A5's value set to 5
row.getCell("name").value = "Zeb"; // B5's value set to "Zeb" - assuming column 2 is still keyed by name
row.getCell("C").value = new Date(); // C5's value set to now

// Get a row as a sparse array
// Note: interface change: worksheet.getRow(4) ==> worksheet.getRow(4).values
row = worksheet.getRow(4).values;
expect(row[5]).toEqual("Kyle");

// assign row values by contiguous array (where array element 0 has a value)
row.values = [1,2,3];
expect(row.getCell(1).value).toEqual(1);
expect(row.getCell(2).value).toEqual(2);
expect(row.getCell(3).value).toEqual(3);

// assign row values by sparse array  (where array element 0 is undefined)
var values = []
values[5] = 7;
values[10] = "Hello, World!";
row.values = values;
expect(row.getCell(1).value).toBeNull();
expect(row.getCell(5).value).toEqual(7);
expect(row.getCell(10).value).toEqual("Hello, World!");

// assign row values by object, using column keys
row.values = {
    id: 13,
    name: "Thing 1",
    dob: new Date()
};

// Iterate over all rows that have values in a worksheet
// Note: interface change - argument order is now row, rowNumber
worksheet.eachRow(function(row, rowNumber) {
    console.log("Row " + rowNumber + " = " + JSON.stringify(row.values));
});

// Iterate over all non-null cells in a row
row.eachCell(function(cell, colNumber) {
    console.log("Cell " + colNumber + " = " + cell.value);
});

## Handling Individual Cells

```javascript
// Modify/Add individual cell
worksheet.getCell("C3").value = new Date(1968, 5, 1);

// query a cell's type
expect(worksheet.getCell("C3").type).toEqual(Excel.ValueType.Date);

Merged Cells

// merge a range of cells
worksheet.mergeCells("A4:B5");

// merge by top-left, bottom-right
worksheet.mergeCells("G10", "H11");
worksheet.mergeCells(10,11,12,13); // top,left,bottom,right

// ... merged cells are linked
worksheet.getCell("B5").value = "Hello, World!";
expect(worksheet.getCell("A4").value).toBe(worksheet.getCell("B5").value);
expect(worksheet.getCell("A4")).toBe(worksheet.getCell("B5").master);

Cell Styles

Number Formats

// display value as "1 3/5"
ws.getCell("A1").value = 1.6;
ws.getCell("A1").numFmt = "# ?/?";

// display value as "1.60%"
ws.getCell("B1").value = 0.016;
ws.getCell("B1").numFmt = "0.00%";

Fonts

// for the wannabe graphic designers out there
ws.getCell("A1").font = {
    name: "Comic Sans MS",
    family: 4,
    size: 16,
    underline: true,
    bold: true
};

// for the graduate graphic designers...
ws.getCell("A2").font = {
    name: "Arial Black",
    color: { argb: "FF00FF00" },
    family: 2,
    size: 14,
    italic: true
};

// note: the cell will store a reference to the font object assigned.
// If the font object is changed afterwards, the cell font will change also...
var font = { name: "Arial", size: 12 };
ws.getCell("A3").font = font;
font.size = 20; // Cell A3 now has font size 20!

// Cells that share similar fonts may reference the same font object after
// the workbook is read from file or stream

Font Property	Description	Example Value(s)
name	Font name.	"Arial", "Calibri", etc.
family	Font family. An integer value.	1,2,3, etc.
scheme	Font scheme.	"minor", "major", "none"
charset	Font charset. An integer value.	1, 2, etc.
color	Colour description, an object containing an ARGB value.	{ argb: "FFFF0000"}
bold	Font weight	true, false
italic	Font slope	true, false
underline	Font underline style	true, false, "none", "single", "double", "singleAccounting", "doubleAccounting"
strike	Font strikethrough	true, false
outline	Font outline	true, false

Alignment

// set cell alignment to top-left, middle-center, bottom-right
ws.getCell("A1").alignment = { vertical: "top", horizontal: "left" };
ws.getCell("B1").alignment = { vertical: "middle", horizontal: "center" };
ws.getCell("C1").alignment = { vertical: "bottom", horizontal: "right" };

// set cell to wrap-text
ws.getCell("D1").alignment = { wrapText: true };

// set cell indent to 1
ws.getCell("E1").alignment = { indent: 1 };

// set cell text rotation to 30deg upwards, 45deg downwards and vertical text
ws.getCell("F1").alignment = { textRotation: 30 };
ws.getCell("G1").alignment = { textRotation: -45 };
ws.getCell("H1").alignment = { textRotation: "vertical" };

Valid Alignment Property Values

horizontal	vertical	wrapText	indent	readingOrder	textRotation
left	top	true	integer	rtl	0 to 90
center	middle	false		ltr	-1 to -90
right	bottom				vertical
fill	distributed
justify	justify
centerContinuous
distributed

Borders

// set single thin border around A1 ws.getCell("A1").border = { top: {style:"thin"}, left: {style:"thin"}, bottom: {style:"thin"}, right: {style:"thin"} };

// set double thin green border around A3 ws.getCell("A3").border = { top: {style:"double", color: {argb:"FF00FF00"}}, left: {style:"double", color: {argb:"FF00FF00"}}, bottom: {style:"double", color: {argb:"FF00FF00"}}, right: {style:"double", color: {argb:"FF00FF00"}} };

// set thick red cross in A5 ws.getCell("A5").border = { diagonal: {up: true, down: true, style:"thick", color: {argb:"FFFF0000"}} };

Valid Border Styles

• thin
• dotted
• dashDot
• hair
• dashDotDot
• slantDashDot
• mediumDashed
• mediumDashDotDot
• mediumDashDot
• medium
• double
• thick

Reading XLSX

// read from a file
var workbook = new Excel.Workbook();
workbook.xlsx.readFile(filename)
    .then(function() {
        // use workbook
    });

// pipe from stream
var workbook = new Excel.Workbook();
stream.pipe(workbook.xlsx.createInputStream());

Writing XLSX

// write to a file
var workbook = createAndFillWorkbook();
workbook.xlsx.writeFile(filename)
    .then(function() {
        // done
    });

// write to a stream
workbook.xlsx.write(stream)
    .then(function() {
        // done
    });

Value Types

The following value types are supported.

Enum Name	Enum(*)	Description	Example Value
Excel.ValueType.Null	0	No value.	null
Excel.ValueType.Merge	1	N/A	N/A
Excel.ValueType.Number	2	A numerical value	3.14
Excel.ValueType.String	3	A text value	"Hello, World!"
Excel.ValueType.Date	4	A Date value	new Date()
Excel.ValueType.Hyperlink	5	A hyperlink	{ text: "www.mylink.com", hyperlink: "http://www.mylink.com" }
Excel.ValueType.Formula	6	A formula	{ formula: "A1+A2", result: 7 }

Release History

Version	Changes
0.0.9	Number Formats
0.1.0	Bug Fixes "<" and ">" text characters properly rendered in xlsx Better Column control Better Row control
0.1.1	Bug Fixes More textual data written properly to xml (including text, hyperlinks, formula results and format codes) Better date format code recognition Cell Font Style
0.1.2	Fixed potential race condition on zip write
0.1.3	Cell Alignment Style Row Height Some Internal Restructuring
0.1.4	Bug Fixes Now handles 10 or more worksheets in one workbook theme1.xml file properly added and referenced Cell Borders

Interface Changes

Every effort is made to make a good consistent interface that doesn't break through the versions but regrettably, now and then some things have to change for the greater good.

Interface Breaks in 0.1.0

Worksheet.eachRow

The arguments in the callback function to Worksheet.eachRow have been swapped and changed; it was function(rowNumber,rowValues), now it is function(row, rowNumber) which gives it a look and feel more like the underscore (_.each) function and prioritises the row object over the row number.

Worksheet.getRow

This function has changed from returning a sparse array of cell values to returning a Row object. This enables accessing row properties and will facilitate managing row styles and so on.

The sparse array of cell values is still available via Worksheet.getRow(rowNumber).values;

Interface Breaks in 0.1.1

cell.model

cell.styles renamed to cell.style