nodejs implements word preview

With the development of the times, our document processing methods are also constantly changing. In the past, we might use various document processing software to edit and read documents, but now, more and more people are more accustomed to processing documents on the Internet. In terms of realizing online document processing, Node.js has become a very powerful tool.

Word preview is undoubtedly one of the most common needs in document processing. When users upload a Word document, they need to preview it on the web page and perform some basic operations such as browsing and printing. This is a requirement that many companies and individuals must meet. This article will introduce how to use Node.js to implement online preview of Word documents.

1. Prerequisite knowledge

Before starting, you first need to understand some prerequisite knowledge.

1. Office extended field name

The text, pictures, tables and other elements in the Word document will be stored in a "Office Open XML" when it is saved as a document. .docx" or ".doc" file. In this file, each element will be assigned a unique extended property name (Extended Property Name).

In our application, we need to use some commonly used extended field names, as shown in the following table:

Type	Extension field name
Text	docProps/core.xml/title
Creator	docProps/core.xml/creator
Creation time	docProps/core.xml/created
Modifier	docProps/core.xml/lastModifiedBy
Modification time	docProps/core.xml/modified
Picture	word/media/image1
Table	word/document.xml/table

2. Node.js

Node.js is a runtime environment that uses JavaScript language for server-side programming. Through it, we can use JavaScript to write server-side applications to provide a variety of services. Node.js uses an event-driven, non-blocking I/O model to ensure high performance and very good scalability.

In this article, we will use Node.js to read the content in the Word document and convert the Word document to HTML.

3. Docxtemplater

Docxtemplater is a template engine based on Node.js, which can read Word documents and modify them. We will use Docxtemplater to modify the Word document to implement the online preview function.

2. Implementation process

Next, we will introduce how to use the above technology to achieve online preview of Word documents.

1. Install the necessary modules

We use Node.js to implement online preview of Word documents, so we need to install some necessary modules. In this article, the modules we need to use are docxtemplater, unzip and fs.

You can use the npm command to install these modules:

npm install docxtemplater unzip fs

2. Read the content of the Word document

Before using docxtemplater to modify the Word document, we need to read it first Get the content of the Word document. We can use the built-in fs module of Node.js to implement file reading. Before reading, we need to decompress the ".docx" file.

// 解压docx文件
function unzipDocx(file) {
  return new Promise((resolve) => {
    const extractPath = path.join(__dirname, 'extracted');
    const unzipper = new Unzipper();

    mkdirp(extractPath);
    unzipper.on('extract', resolve);
    fs.createReadStream(file).pipe(unzipper).pipe(fs.createWriteStream(extractPath));
  });
}

// 读取Word文档内容
function readDocx(file) {
  const ext = path.extname(file);

  return ext === '.docx' ? readDocxXml(file) : '';
}

function readDocxXml(file) {
  const contentXml = path.join(__dirname, `extracted/word/document.xml`);

  return fs.readFileSync(contentXml);
}

3. Convert Word documents to HTML

Docxtemplater can convert Word documents to HTML, which is very convenient. We only need to specify the output template as HTML when calling the template engine.

// 将Word文档转换为HTML
async function parseDocx(content) {
  const templater = new Docxtemplater();

  templater.loadZip(new JSZip(content));
  templater.setData({});

  // 替换表格为HTML
  templater.attachModule(new HtmlModule());
  templater.compile();
  const { renderedHtml } = templater.getRendered();

  return renderedHtml;
}

It is worth noting that in the process of converting Word documents to HTML, we use the HtmlModule module of Docxtemplater. This module can convert tables and other content in Word documents into HTML.

4. Run the application

After completing the above steps, we will get an application that can preview Word documents. In this application, we will use Express to provide services.

const express = require('express');
const app = express();

app.get('/', (req, res) => {
  const filePath = req.query.file;

  if (!filePath) {
    res.send(`请指定需要预览的Word文档文件路径，如：http://localhost:3000/?file=/path/to/your/file.docx`);
    return;
  }

  unzipDocx(filePath).then(() => {
    const content = readDocx(filePath);
    parseDocx(content).then(html => {
      res.send(html);
    });
  });
});

app.listen(3000, () => console.log('应用程序已启动，访问 http://localhost:3000 即可查看。'));

After running this application, we can access http://localhost:3000/?file=/path/to/your/file.docx in the browser to preview the Word document.

3. Summary

It is very convenient to use Node.js to achieve online preview of Word documents. With the help of Docxtemplater, a template engine, we can quickly convert Word documents into HTML, and then through some simple operations, we can implement the preview function in the browser.

It should be noted that during the process of using Node.js to preview Word documents, we need to protect the user's file security. We can use passwords, access rights, etc. to protect users' files. At the same time, we also need to pay special attention to the security of the server to avoid problems such as leaks.

Node.js is widely used in Web development. Whether it is for online document preview or other Web application development, Node.js can become a very powerful tool. I believe that Node.js will become more and more popular among web developers in the future.

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