TinyMCE's HTML Stripping: Why JavaScript Disappears Within Tags
TinyMCE, a popular rich text editor, is known for its powerful features and user-friendly interface. However, you might encounter a puzzling issue: TinyMCE strips out JavaScript code embedded within HTML tags. This can be frustrating when you need to inject dynamic behavior directly into your content.
Scenario:
Imagine you're using TinyMCE to create a blog post where you want to include a simple interactive element. You write the following code:
<div id="my-element">
<script>
console.log("This JavaScript code should execute!");
</script>
</div>
After saving the post, you'll find that the <script> tag remains, but the JavaScript code itself is gone!
Why Does This Happen?
TinyMCE has a built-in security mechanism that sanitizes user-submitted content to prevent malicious code injection. By default, it removes any JavaScript code that isn't placed within a <script> tag.
Analysis:
While this security measure is important, it can hinder developers who legitimately need to embed JavaScript within HTML. There are a few ways to address this issue:
-
Use TinyMCE's Configuration:
-
valid_elements: This setting controls which HTML elements are allowed within TinyMCE. You can specify<script>as a valid element and include it in your configuration:tinymce.init({ selector: 'textarea', valid_elements: 'script[*]' }); -
valid_children: This setting allows you to define which child elements are allowed within other elements. For example, you can allow<script>tags as children of<div>:tinymce.init({ selector: 'textarea', valid_children : "+div[script]" });
-
-
Encode Your JavaScript:
- TinyMCE interprets JavaScript code within HTML tags as potentially dangerous. You can use a technique like HTML encoding to circumvent this. Instead of embedding the JavaScript directly, you can encode it as a string and then decode it using JavaScript on the front-end.
<div id="my-element"> <script> const encodedScript = "console.log(%22This+JavaScript+code+should+execute!%22);"; eval(decodeURIComponent(encodedScript)); </script> </div>
Important Considerations:
- Security: While these solutions allow you to embed JavaScript, it's crucial to ensure the code is properly sanitized to prevent cross-site scripting (XSS) vulnerabilities.
- Alternatives: Consider using alternative methods like custom plugins or backend processing to inject JavaScript behavior if the security implications of direct embedding are too high.
Conclusion:
TinyMCE's HTML sanitization is a valuable security feature, but it can create unexpected behavior when working with JavaScript. By understanding the limitations and utilizing the provided configuration options or alternative solutions, you can effectively manage JavaScript within your TinyMCE content.
References:
- TinyMCE Documentation: https://www.tiny.cloud/docs/
- HTML Encoding: https://www.w3schools.com/html/html_entities.asp
