Fix MathJax Issue: Tex-chtml.js On GitHub Pages

Nov 24, 2025 by Alex Johnson 48 views

Addressing MathJax Rendering Issues with tex-chtml.js on GitHub Pages and Jekyll

If you're encountering problems with MathJax rendering on your GitHub Pages site, especially when using Jekyll and tex-chtml.js, you're not alone. This article delves into a common issue where tex-chtml.js fails to properly render mathematical equations, leading to garbled text and missing formulas. We'll explore the problem, its causes, and potential solutions to ensure your mathematical content displays correctly.

Understanding the MathJax and Jekyll Issue

When using MathJax with Jekyll on GitHub Pages, a peculiar problem can arise where mathematical equations, both inline and display, are not rendered correctly. Instead of seeing beautifully formatted formulas, you might encounter plain text interspersed with concatenated words, making the content unreadable. For example, an equation like "Let $(a_n)_{n \ge 1}$ be a sequence of positive real numbers defined by $a_1 = \frac{1}{2}$ and $a_{n + 1} = a^2_n + a_n$ ," might render as "Let $(a_n){n \ge 1}$ beasequenceofpositiverealnumbersdefinedby $a_1 = \frac{1}{2}$ anda{n + 1} = a^2_n + a_n$,". This issue specifically surfaces after Jekyll builds the site for GitHub Pages, while the raw Markdown file displays perfectly on GitHub or when viewed locally. This discrepancy points to a conflict or misconfiguration during the Jekyll build process.

Reproducing the Issue: A Step-by-Step Guide

To illustrate the problem, let’s walk through the steps to reproduce this MathJax rendering issue on GitHub Pages using Jekyll:

Set up a Jekyll/GitHub Pages Repository: Begin by creating a new repository on GitHub. You can use the default settings without any special themes to keep things simple. This ensures a clean environment to test the MathJax integration.
Create a Markdown File with MathJax: Within your repository, create a new Markdown file (e.g., test.md). Add the following code snippet, which includes the necessary MathJax configuration and a sample mathematical expression:
```
<script>
MathJax = {
  tex: {
    inlineMath: [['{{content}}#39;, '{{content}}#39;], ['\${', '\}{{content}}#39;]]
  }
};
</script>
<script id="MathJax-script" async
  src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-chtml.js">
</script>

# Test

Let $(a_n)_{n \ge 1}$ be a sequence of positive real numbers defined by $a_1 = \frac{1}{2}$ and $a_{n + 1} = a^2_n + a_n$,
```
This code snippet configures MathJax to recognize inline math enclosed in single dollar signs ($) and escaped parentheses (${ and }$). It also loads the tex-chtml.js script from the MathJax CDN, which is responsible for rendering TeX-based mathematical notation in HTML.
Commit and Publish: Commit the Markdown file to your repository and push the changes to GitHub. This action triggers GitHub Pages to build your site using Jekyll.
View the Published Page: Navigate to your GitHub Pages URL (usually https://<your-username>.github.io/<repository-name>/test.html) and observe the rendering. If the issue is present, you'll notice that the mathematical expression is not rendered correctly. Instead, you'll see a jumbled mess of text, as described earlier.

By following these steps, you can easily replicate the MathJax rendering issue and confirm that it is indeed occurring in your environment. This is the first step towards finding a solution.

Technical Details and Configuration

To further understand the issue, it's crucial to consider the technical details and configuration involved. The problem often manifests with specific versions of MathJax and under certain conditions. Here are some key details to keep in mind:

MathJax Version: The issue has been observed with MathJax v3, specifically version 3.2.2 (the latest served by https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-chtml.js). This suggests that the problem might be related to changes or bugs introduced in this version or its interaction with Jekyll.
Client OS and Browser: The issue is not specific to a particular operating system or browser. It has been reported on both MacOS and Windows 11, and across browsers like Chrome and Brave. This indicates that the problem is more likely related to the rendering process or the interaction between MathJax and Jekyll, rather than client-specific factors.
MathJax Configuration: The MathJax configuration used in the example is relatively standard:
```
MathJax = {
  tex: {
    inlineMath: [['{{content}}#39;, '{{content}}#39;], ['\${', '\}{{content}}#39;]]
  }
};
```
This configuration tells MathJax to recognize inline math enclosed in single dollar signs and escaped parentheses. The simplicity of this configuration suggests that the issue is not due to complex or conflicting settings.
Loading MathJax: MathJax is loaded via a <script> tag that points to the CDN:
```
<script id="MathJax-script" async
  src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-chtml.js">
</script>
```
The async attribute indicates that the script is loaded asynchronously, which is generally a good practice for performance. However, it's possible that this asynchronous loading could interact with Jekyll in unexpected ways.

Understanding these technical details helps narrow down the potential causes of the issue and guides the search for solutions. It highlights the importance of considering the specific MathJax version, the loading method, and the interaction with Jekyll.

Potential Causes and Solutions for MathJax Rendering Issues

Given the technical details and the steps to reproduce the issue, let's explore some potential causes and solutions for the MathJax rendering problems on GitHub Pages with Jekyll. This issue can stem from various factors, including script loading order, Jekyll's processing of Markdown, and conflicts between MathJax and Jekyll's rendering engine.

1. Script Loading Order and Asynchronous Loading

One potential cause is the asynchronous loading of the MathJax script (tex-chtml.js). The async attribute in the <script> tag allows the browser to download the script in the background without blocking the parsing of the HTML. While this improves page load time, it can also lead to a race condition where MathJax is not fully loaded and initialized before the page content, including the mathematical expressions, is processed. Jekyll might render the page before MathJax has a chance to typeset the equations, resulting in the garbled output.

Solution:

Remove the async attribute: Try removing the async attribute from the <script> tag. This forces the browser to load and execute the script synchronously, ensuring that MathJax is fully initialized before the page content is rendered. While this might slightly increase the initial page load time, it can resolve the rendering issue.
```
<script id="MathJax-script"
  src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-chtml.js">
</script>
```
Defer Script Loading: Alternatively, you can use the defer attribute. The defer attribute tells the browser to download the script in the background but execute it after the HTML parsing is complete. This can provide a balance between performance and correct rendering.
```
<script id="MathJax-script" defer
  src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-chtml.js">
</script>
```

2. Jekyll's Markdown Processing

Jekyll uses a Markdown engine (typically Kramdown) to convert Markdown files into HTML. It's possible that Jekyll's Markdown processing is interfering with MathJax's ability to correctly identify and render mathematical expressions. For example, Jekyll might be escaping or modifying characters that MathJax relies on, such as dollar signs or backslashes.

Solution:

Adjust Markdown Configuration: Jekyll's Markdown engine can be configured to handle certain characters and syntax differently. Try adjusting the Markdown configuration in your _config.yml file to ensure that MathJax's syntax is not being inadvertently modified.

For example, you can try disabling certain extensions or features that might be interfering with MathJax. Refer to the Jekyll documentation for details on Markdown configuration options.
Use a Different Markdown Engine: If adjusting the configuration doesn't work, consider using a different Markdown engine. Jekyll supports several Markdown engines, such as Redcarpet and CommonMark. Switching to a different engine might resolve compatibility issues with MathJax.

3. Conflicts with Jekyll's Rendering Engine

Jekyll's rendering engine might be conflicting with MathJax in some way. This could be due to CSS styles, JavaScript interactions, or other factors that are affecting how MathJax renders the equations.

Solution:

Isolate the Issue: Try creating a minimal test case with only the MathJax script and the mathematical expressions. This helps determine if the issue is specific to certain parts of your site or a general problem. If the minimal test case works, the issue is likely due to a conflict with other elements on your site.
Check for CSS Conflicts: Inspect your site's CSS to see if there are any styles that might be affecting MathJax's rendering. For example, styles that modify font sizes, line heights, or text wrapping could interfere with how MathJax displays equations.
JavaScript Conflicts: If you're using other JavaScript libraries or scripts on your site, there might be conflicts with MathJax. Try disabling other scripts temporarily to see if that resolves the issue.

4. CDN Issues or Network Problems

In rare cases, the issue might be due to problems with the CDN hosting the MathJax script or network connectivity issues. If the script cannot be loaded correctly, MathJax will not be able to render the equations.

Solution:

Check CDN Status: Verify that the CDN hosting the MathJax script is functioning correctly. You can check the CDN's status page or try accessing the script directly in your browser.
Use a Different CDN or Host Locally: If the CDN is experiencing issues, try using a different CDN or hosting the MathJax script locally on your site. This ensures that you have control over the script's availability.

By systematically addressing these potential causes and trying the suggested solutions, you can effectively troubleshoot MathJax rendering issues on GitHub Pages with Jekyll. Remember to test each solution individually to determine its effectiveness and avoid introducing new problems.

Conclusion: Restoring Mathematical Clarity on Your GitHub Pages Site

Encountering rendering issues with MathJax on GitHub Pages, especially when using Jekyll, can be a frustrating experience. However, by understanding the potential causes – such as script loading order, Jekyll's Markdown processing, conflicts with the rendering engine, and CDN issues – you can systematically troubleshoot and resolve the problem. Whether it's adjusting script attributes, tweaking Markdown configurations, or addressing CSS and JavaScript conflicts, there are several avenues to explore.

By implementing the solutions discussed in this article, you can ensure that your mathematical content is displayed correctly, maintaining the clarity and precision of your work. Remember to test each solution thoroughly and isolate the root cause of the issue to achieve the best results. With a bit of patience and persistence, you can restore mathematical clarity to your GitHub Pages site and provide a seamless reading experience for your audience.

For further information on MathJax and its integration, you can visit the official MathJax website.