Nodejs server-side rendering font cannot be downloaded

With the continuous development of the Internet, front-end development is becoming more and more important. Traditional static page rendering can no longer meet the needs of modern websites, and Server Side Rendering (SSR) has become a popular solution. Node.js is a very popular server-side Javascript running environment, which can be used to implement server-side rendering. However, sometimes we encounter a problem, that is, the nodejs server-side rendering font cannot be downloaded.

Why does this problem occur? During the server-side rendering process, an HTML string is generated and returned to the client. The HTML contains the corresponding font reference address. When a client requests resources for these fonts, the server should be able to respond correctly and return the file. However, in some cases, this does not happen. In this article, we will explore the possible causes of this problem and provide some solutions.

1. Cross-domain request issues

When using server-side rendering, you are likely to encounter cross-domain request issues. When the font resource file and the HTML file are located on servers with different domain names and ports, the client will send a cross-domain request. At this time, the server may not set the response header correctly, causing the browser to refuse to download the font file. In Node.js, you can use the cors middleware library to solve this problem. After using the cors library, you only need to set the response header of the font file on the server side to allow cross-domain requests, as shown in the following example:

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

app.use(cors());

app.get('/fonts/:fontName', (req, res) => {
  const fontName = req.params.fontName;
  // 发送字体文件
  res.sendFile(fontName, { root: 'fonts/' });
});

app.listen(8080, () => {
  console.log('Server started on http://localhost:8080');
});

2. Font file path Problem

When rendering on the server side, the path problem of the font file often occurs. In development, either absolute file paths or relative file paths may be used. However, these paths may change when deploying to production. In this case, it's better to use a relative path to the root of the website so that the path to the font file will always be correct.

3. Font file does not exist

When the font file does not exist, the server will return a 404 error. At this time, the client cannot download the font. In this case we should check if the font file exists and do error handling before sending the response to the client.

const fontPath = path.join(__dirname, 'fonts/Roboto-Regular.ttf');

fs.access(fontPath, fs.constants.F_OK, (err) => {
  if (err) {
    console.error(`Error: Could not access file ${fontPath}`);
    res.sendStatus(404);
  } else {
    // 发送字体文件
    res.sendFile('Roboto-Regular.ttf', { root: 'fonts/' });
  }
});

4. Missing mime type

In server-side rendering, the problem of missing mime type may also occur. The MIME (Multipurpose Internet Mail Extensions) type indicates the type of file and how to process the file. If the correct MIME type is missing, the browser may not correctly recognize the file type, preventing the font from being downloaded. In this case, we can use the mime library to help set the correct MIME type.

const mime = require('mime');

app.get('/fonts/:fontName', (req, res) => {
  const fontName = req.params.fontName;
  const fontPath = path.join(__dirname, 'fonts/', fontName);

  // 设置字体文件的MIME类型
  res.setHeader('Content-Type', mime.getType(fontPath));

  // 发送字体文件
  res.sendFile(fontName, { root: 'fonts/' });
});

In short, when there is a problem that nodejs server-side rendering fonts cannot be downloaded, we should try to solve the cross-domain request problem, correctly set the path of the font file, handle the situation where the font file does not exist, and correctly set the MIME type . All of the above methods can help us solve this problem and make server-side rendering smoother and more efficient.

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