Introduction to node-xlsx

node-xlsx is a powerful library for handling Excel files in Node.js applications. Whether you need to parse, read, or write .xlsx files, node-xlsx provides a straightforward API to achieve your goals. This article introduces node-xlsx and provides dozens of useful API explanations with code snippets to help you get started.

Installation of node-xlsx

First, install the library using npm:

  npm install node-xlsx

Loading an Excel File

To load an Excel file, use the following API:

  
    const xlsx = require('node-xlsx').default;
    const workSheets = xlsx.parse('path/to/file.xlsx');
    console.log(workSheets);
  

Reading Sheet Data

To access sheet data, you can loop through the sheets:

  
    workSheets.forEach(sheet => {
      console.log(sheet.name);
      console.log(sheet.data);
    });
  

Creating a New Excel File

To create a new Excel file, you can define the data and write it to a file:

  
    const data = [
      ["Name", "Age", "City"],
      ["John Doe", 30, "New York"],
      ["Jane Doe", 25, "Los Angeles"]
    ];
    
    const buffer = xlsx.build([{ name: "Sheet 1", data: data }]);
    require('fs').writeFileSync('output.xlsx', buffer);
  

Adding Sheets to an Excel File

You can add multiple sheets to an Excel file:

  
    const sheets = [
      { name: "Sheet 1", data: [["A1", "B1"], ["A2", "B2"]] },
      { name: "Sheet 2", data: [["C1", "D1"], ["C2", "D2"]] }
    ];
    const buffer = xlsx.build(sheets);
    require('fs').writeFileSync('multiSheetOutput.xlsx', buffer);
  

Complete App Example

Below is a simple Node.js app that reads an Excel file, processes the data, and writes a new Excel file with updated information:

  
    // Importing the library
    const xlsx = require('node-xlsx').default;
    const fs = require('fs');

    // Reading the input file
    const workSheets = xlsx.parse('input.xlsx');
    const data = workSheets[0].data;

    // Adding a new column with computed values
    const processedData = data.map((row, index) => {
      if (index === 0) {
        row.push('Processed Value');
      } else {
        row.push(Math.random());
      }
      return row;
    });

    // Creating a new sheet with the processed data
    const buffer = xlsx.build([{ name: 'Processed Data', data: processedData }]);
    fs.writeFileSync('processed_output.xlsx', buffer);

    console.log('Processing complete and file saved as processed_output.xlsx');
  

Conclusion

The node-xlsx library is a versatile tool for developers working with Excel files in Node.js. With its easy-to-use APIs, you can quickly read, write, and manipulate Excel data. We hope the provided examples help you integrate node-xlsx into your projects seamlessly.

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